hi justin thanks a lot for your kind answer!
I downloaded the jar files I was missing and now my project includes the following:
                    richfaces-components-api-4.0.0.Final.jar
                    richfaces-components-ui-4.0.0.Final.jar
                    richfaces-core-api-4.0.0.Final.jar
                    richfaces-core-impl-4.0.0.Final.jar
                    guava-r09.jar 
                    cssparser-0.9.5.jar
                    sac-1.3.jar
 
If I change the web.xml and include the Filter tag as shown below I get the following exception:
GRAVE: WebModule[/WebApplication1]PWC1270: Exception starting filter richfaces
java.lang.InstantiationException
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:124)
    at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4625)
......
Caused by: java.lang.ClassNotFoundException: org.ajax4jsf.Filter
    at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1518)
    at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1368)
    at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:252)
    at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:120)
    ... 47 more
 
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <filter>
        <display-name>RichFaces Filter</display-name> 
        <filter-name>richfaces</filter-name> 
        <filter-class>org.ajax4jsf.Filter</filter-class> 
    </filter> 
    <filter-mapping>
       <filter-name>richfaces</filter-name> 
       <servlet-name>Faces Servlet</servlet-name>
       <dispatcher>REQUEST</dispatcher>
       <dispatcher>FORWARD</dispatcher>
       <dispatcher>INCLUDE</dispatcher>
    </filter-mapping>
    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>faces/index.xhtml</welcome-file>
    </welcome-file-list>
    <!-- Plugging the "Blue Sky" skin into the project -->
    <context-param>
            <param-name>org.richfaces.SKIN</param-name>
            <param-value>blueSky</param-value>
    </context-param>
 
    <!-- Making the RichFaces skin spread to standard HTML controls -->
    <context-param>
        <param-name>org.richfaces.CONTROL_SKINNING</param-name>
        <param-value>enable</param-value>
    </context-param>
</web-app>
 
If I remove the <filter> and <filter-mapping>, the deployment succeeds, but all the problems I had yesterday remain unchanged... 
This is my Bean:
package src;
 
 
import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.event.ActionEvent; 
@ManagedBean
@SessionScoped
public class EchoBean implements Serializable{
 
    public EchoBean() {
    }
    private String name;
    private Integer count;
    public Integer getCount() {
        return count;
    }
    public void setCount(Integer count) {
        this.count = count;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void countListener(ActionEvent e){
        count = name.length();
    }
    
}
And this my facelet: 
 
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:rich="http://richfaces.org/rich"
    xmlns:a4j="http://richfaces.org/a4j">
    <body>
<h:form id="form">
    <rich:panel style="width:50%">
        <h:panelGrid columns="2">
            <h:outputText value="Name:"/>
            <h:inputText value="#{echoBean.name}"/>
            <h:outputText value="Echo:"/>
            <h:outputText id ="name" value="#{echoBean.name}"/>
            <h:outputText value="Count: "/>
            <h:outputText id ="count" value="#{echoBean.count}"/>
        </h:panelGrid>
        <a4j:commandButton value="Submit" actionListener="#{echoBean.countListener()}"  />
    </rich:panel>
    
</h:form>
</body>
</html>
 
Now the waring is: The form component needs to have a UIForm in its ancestry. Suggestion: enclose the necessary components within <h:form> 
and for the listener I get the following exception when I submit the form:
GRAVE: JSF1073: javax.faces.event.AbortProcessingException caught during processing of INVOKE_APPLICATION 5 : UIComponent-ClientId=form:j_idt10, Message=Method countListener not found
GRAVE: Method countListener not found
javax.faces.event.AbortProcessingException: Method countListener not found
    at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:182)
    at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
    at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
    at javax.faces.component.UICommand.broadcast(UICommand.java:300)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:409)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1534)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:326)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:227)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:170)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:822)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:719)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1013)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:662)
Caused by: javax.el.MethodNotFoundException: Method countListener not found
    at javax.el.BeanELResolver.findMethod(BeanELResolver.java:717)
    at javax.el.BeanELResolver.invoke(BeanELResolver.java:466)
    at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:254)
    at com.sun.el.parser.AstValue.invoke(AstValue.java:228)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:297)
    at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:153)
    ... 34 more
 
Furthermore, NetBeans displays an error message if I try to add reRender="name, count" to a4j:commandButton (which let me think there is a configuration error somewhere...)... 
Do you have any new Idea? 
 
Thanks again
bye!