Kernel panic after using Android Emulator for Mac OS X Lion
It appears to be, as you suspected, the Android emulator that is causing the issue.  Some users have filed an issue on Google Code.  If you scroll down past all of the "Me Too's," you'll actually find useful information; there appears to be a workaround involving /Applications/Eclipse.app/Contents/MacOS/eclipse.ini for some.


  I increased the heap space used by Eclipse, and haven't experienced this problem since.
  
  In eclipse.ini I used the following values:

--launcher.XXMaxPermSize256m

-Xms256m

-Xmx1024m



The same issue has a duplicate. In this thread, they mentioned a slightly different method where they added -vmargs between --launcher.XXMaxPermSize256m and -Xms256m 

And I assume you've installed Intel Hardware Accelerated Execution Manager, as this is a requirement for  the Android Emulator.  However, in the comments, people note that it doesn't work with Mountain Lion and they had to disable it for Android Emulator to work.

For your question about the number of installs Lion from the App Store will give you, this is directly from Apple's EULA (emphasis added):


  (i) to download, install, use and run for personal, non-commercial
  use, one (1) copy of the Apple  Software directly on each
  Apple-branded computer running Mac OS X Snow Leopard or Mac OS X  Snow
  Leopard Server (“Mac Computer”) that you own or control;


So, assuming that this is for personal, non-commercial use, Apple lets you install Lion as many times as you like on the Macs that you own or control.