Bootcamp is just a boot manager. IT allows Mac users to install Vista or XP on their Mac and boot between either Windows or OS X. It isnt emulation at all.
Emulations is like using ZSNES to play SNES games on your PC. It emulates the SNES and allows for the games to work.
Compatability mode is what Vista does, and XP as well, to basically trick itself into thinking it is running as a different OS to make apps run better. I have soem games on XP that i have to use compatability mode for cause they are Windows 95 games. Same can be done with Vista. Use compatability mode to made it run like they were in XP. Creates less problems and allows the apps to run correctly.
That is number 1. Onto number 2.
You CPU has to be 64 Bit. that is the major part. The rest the major driver you will have to check for are sound and video.
#3.) Yes Vista is great when it comes to driver install. Most of the drivers installed on my Vista are straight from Creative and nVidia. That was thru Windows Update. So you should be able to get the latest drivers right from there.
#4.) Overclocking is the same with 32Bit/64Bit when done thru the BIOS.
#5.) A 16 Bit program is just that. It is a program that was written with only 16 Bit archatechture. ^$ Bit only sees 64 and 32. So apps that are for Windows 95 wouldnt work since they are 16 Bit program. Most apps now a days are 32 and some are 64 bit programs. But a few are still stuck at that 16 bit stage and have to move on. But most of those you can find a good substitute for.
#6)Windows Vista RTM Software Compatibility List - IeXwiki
That page can answer your question easily. It give you the full list of working and non working applications that work on Vista. I dont know how recent it was updated but that is the best way to find out if your apps are gonna work.