Moving from D1 to D2, and Im confused.

[undeliverable]

My D1 finally died and I got my hands on a cheap D2. I was winding up to flash a new ROM on my D2 but I started seeing terms like "2nd Init ROM" and now I'm suddenly not sure what to do. I think I was horribly spoiled by the unlocked bootloader on my D1 and I was able to flash any ROM without fear. (I was generally running SS, MIUI or Liquid) The D2 does not seem so forgiving. No overclocking is a bit painful as well, but my D1 wouldnt go over 1Ghz anyway, so that's a wash... So :

What is a 2nd Init ROM, and how do I tell the difference?
Do I need to flash back to stock, re-root and re-run Bootstrap every time I change ROMs?
How easy is it to brick this thing?
Is it possible to unlock the boot loader?
Is it possible to overclock?
Can I really install any DX ROM and have it work OK?
What is the performance penalty for running Boot Manager and having the ROM run off of SD?

I have looked around for these answers and have not found any clear explanations. Any help on these items would be appreciated.

[siriusgamer]

2nd-init is a workaround for the locked bootloader. From what I understand it hijacks the bootloader and it makes it possible to load a custom kernel.
A 2nd-init rom would be Cyanogenmod or MIUI.

Changing roms doesnt require a flash back to stock. Just wipe caches and data in Clockwork and flash the ROM.

Sort of kind of easy.

Not at the moment. But there is a bootloader unlock the the atrix 4g.

Yes. I'm pretty sure overclocking apps for the droid 2/x load something into the kernel that allows overclocking.

No, a droid x rom is for the droid x and a droid 2 rom is for the droid 2. But I think its easy to port roms originally made for a device, to the opposite device.

I dont know, Ive never used boot manager.

[undeliverable]

I know that was a lot of questions to answer and I appreciate the response. I managed to get MIUI on my phone last night without destroying my phone. It runs well so far but I don't know if I will stick with it or not. Thanks again!