Is El Cap beta 2 stable to install on main computer. Will I still be able to work in Xcode and use other apps?
El Capitan beta 2
I've found it to be pretty stable - that said, it's still a developer preview so, if you need stability and it's your main OS, don't install it. If you create a seperate partition for it though, then you're mitigating most of the risks and you'll proabably be fine
As for Xcode, it won't run 6.3.2 without launching it from Terminal (a bit hacky and not really recommended), but obviously 7 works fine.
it's stable enough to run without any peripherals attached. I have a dock and a USB Hub for my MacBook Pro. The hub makes it unstable and goes into a continuous reboot cycle. I can only attach my LaCie external drive to either thunderbold or through USB 3.
The Xcode Beta woks fine on beta 2, I you can upload to the App store fpr pre-release testing