I use the X3 bios which has debug features that can be turned on and off. No problems for NTSC or PAL. Dunno if 4627 will work.
For the rest of your questions, its not neccesary to patch or hack any of your games to work with the debug bios. (Almost-) all games might work with debug bios. The only thing that the debug bios do is to run a different thread that is dedicated to listening for debug requests from the outside. Furthermore, it will apply some "hooks" for the debugger to catch several API's.
So, the programs aren't patched, its the bios...
The only thing I noticed is that some memory exhaustive games, like HALO2, don't like a second thread occupying memory. So, in my collection of 200 games, this was one that didn't worked in a debug environment...
Final thing, you don't need to install M$ XDK & Visual .Net. if you only need screengrabs. There is a nice utility for it that isn't dependend on XDK&Visual .Net. Keep in mind that some tools you have to install on the xbox, however, are also in the XDK...