1. Can I set the start level on servicemix kernel (examples: I only want bundle @ level <= 10 to start)?
You can modify felix.startlevel.framework in etc/config.properties file to set the start level you want the kernel to go up to. This is for the startup though. It can be affected by other factors such as further configuration via shell or JMX.
2. When I deploy may "user developed" bundles how do I set the start level for a specific bundle?
You can control the start level of the bundles in etc/startup.properties. You can add the bundle there with required start level assigned to it.