1) I think the "MainDeployer" could help. It can undeploy/deploy web applications without having to delete/add the WAR file. You will find it in the jmx-console.
The jmx-console should also contain a service representing your web app, and there you should find start/stop methods.
For 2 and 3 I cannot help.
Thanks for your help.
As I use "jmx-console", it is not easy to find that "MainDeployer". Also not every web application has this service. Click on "jboss.system" on the left menu, there is a "service=MainDeployer" on the right menu. When I click on the url of "service=MainDeployer", there is several "stop", "deploy", "undeploy", ... with "invoke" button. I have no idea which "stop" will stop which web application. Really confuse.
Finally, I think "jmx-console" is not a user-friend GUI at all. Also, it cannot help me to do manage the JBoss As or web application.
you were quite near to it ;-). The "deploy" and "undeploy" methods are the right ones. The parameters for them are URLs of deployed files (e.g. in your "deploy" directory).
Unfortunately, at least in some Betas of JBoss 5, they were not working as expected ( https://jira.jboss.org/jira/browse/JBAS-5643 ). So, if you are interested in using them, you should ask in the "AS5" forum about the state of it.
The "stop"/"start" methods will stop/start the MainDeployer service, so I don't advice to click them ;-).
I think you should also find some service which is named like your web app, and this service should contain start/stop methods. So, maybe you can start/stop your web app this way.