Item 1: do a google search for the differences between dvd+r and dvd-r. In a quick summary, there are differences in error correction, and reading/writing methods for higher reliablity with the nod going to dvd+r standard. I always buy my disks from Meritline.com and have always used prograde Tayo Yuden disks - I've never had a bad write in over 100 disks. The price difference is minimal between cheap disks and pro disks. Why chance your data to a poor quality disk.
Item 2: Check my posts on this thread, as it has my storage/archive/backup strategy:
https://www.pentaxforums.com/forums/233231-post29.html
and
https://www.pentaxforums.com/forums/233294-post32.html
Oh, yeah, the files are first stored, and primarily used on my main system on drive d, a data only 250 GB hard drive used for my documents, picture library, music library, etc. It is separate from my c drive (system) so if the system crashes, I just reinstall the system partition and go. I don't have to worry about my data.
The archiving, organization and long term storage and retrieval ability is getting ever more important as our digital domains are getting larger and larger. We have electronic forms of movies, music, pictures, financial and tax data, email correspondence and so on that is becoming of great important to us. In my mind, I don't worry about the hard drive crashing because of the cost in dollars of a new drive, but in the cost of data lost! Not only that, but I would rather spend a little time getting an efficient disaster recovery method laid out now, rather than have to figure out what to install and how to rebuild it when a tragety happens and my drives fail, the house gets hit by lightning, etc. You almost can't afford to NOT treat this like a small business would.