As far as the hard drives go I believe it depends on the connection type and that is all that matters once it is formatted properly and such. The Mac Pro uses SATA 2 or (3.0 GB/s) connections, so any hard drive that is that connection you should be able to just pop into the Mac Pro and have it work. I believe just plain SATA drives will work as well, because I have seen people with the WD Raptors in the Mac Pro. It sounds like your drive should work just fine but you will need to format it for the Mac Pro. I actually installed a 500 GB Seagate from OWC in mine and I am ordering a 750 GB from NewEgg soon.
I also installed at second optical drive in my Mac Pro. I ordered it from SuperMediaStore and it was just a stock Pioneer DVR-111d I believe. I don't know if the Blu-Ray or HD-DVD drives will work in the Mac Pro yet, sorry.
Both of those installations are really easy and you should be able to do it with relative ease. If you have any problems macsales.com has a bunch of good help
videos.