also... do I lose quality if I use compressor to convert it to pro res, and then bring back to h.264 ? and then if use the footage again to edit i bring it back to pro res? I know this sounds weird, but i am trying to figure out the best way to archive and save space on my hard drive...
That all depends on your h.264 transcode settings. You would have to experiment.
I have projects that are transcoded into h.264 for archiving on DVD. But these are the kind of projects where some compression won't matter.. They are already composite DVNTSC videos that don't look all that pretty to begin with. Strictly for documented archiving. So compressing 30-100GB of video down to 1-3.8GB of h.264 video isn't a "How Dare You!" issue.
Best way to figure out what works for you is to test. Use Compressor & do a transcode. Save a temp custom setting which you can tweak. Then re-transcode back to your edit codec ( Pro-Res ) and see what you think. It might be acceptable for what you do with it. It might not...