I also have a new external HD from Apple, and 2 old ones that I've been using with my PC. I don't know if I should be reformatting something…

I have a new version of Windows 7 that I want to use. I would rather not partition the hard drive and only be able to boot into OS at a time. I've read about Parallels Desktop for Mac. It sounds good to me, but idk what I'm doing so I would really appreciate some feedback if anyone knows about it. (I have no problem with the price! I don't need freeware).
Some things I'm wondering:
Will I have full access to my NTFS formatted drives using Windows with parallel?
Can I have access to both my old NTFS HDs and my new "Promise Pegasus R4 RAID system" external HD? (it uses thunderbolt, or whatever thunderbolt does, in case that's important.)
From what I've read, I get the impression that trying to reformat my Apple HDs can cause serious harm. Should I reformat any old HD that I want to use into HFS+ Journaled? The only thing I've ever used is PC and stuff that's made for it so I have no experience with file systems and don't know much about them.
I have read about Paragon (NTFS for Mac). Does anyone know if that would help improve compatibility and would it in any way HURT my computer?
I want to be able to pre-process my footage using avisynth under windows, save the files to my external drive and then use them in my adobe applications which I bought for Mac OS. Post-processing/compression will also be in Windows probably so I really need it to work both ways.
Thanks so much in advance for any advice!!!
Specs:
2.3 GHz Intel Core i7
8GB RAM
500GB Solid State Drive
*Tell me if this topic is too long and I'll split it into two*