Do having multiple MBeans pose performance issues?
No, MBeans themselves are just stubs for JMX access to your application. You could have performance problems if you are sending back a large amount of data (like 100s of attributes or large arrays or something) or making a large number of requests per second. But in themselves, the mbeans are typically singletons and are themselves never a performance sink.
I may end creating 30+ MBeans. I am really concerned if it will be too chatty with JVM.
Again, unless you are requesting data from those mbeans at some high rate, you shouldn't have a problem. We have literally hundreds of mbeans in our various and have seen no performance problem with them.