Personally I dont think this is a good idea- or at least, I'd never do this. Perhaps think of thinning your collection, but I wouldnt rely on a CD-R copy of anything that will get a lot of use. My experience is that CD-Rs scratch faster than CDs (but this may be because Im less careful with CD-Rs, who knows). Ok but now to answer your questions...
It seems that most people agree that CD-Rs will decompose faster than CDs- due to differences in the processes that create them (but Ive read articles that seem not to agree). We dont know when this will happen, obviously because its a new medium but there have been various simulations of aging (apply heat, cold etc), which give ranges of 25 to 100 years.. so who knows (I guess we will know in 25 or 100 years).
You can read pages and pages of dialogue over which are the best CD-Rs to buy- most weigh in that Tiayo Yuden make the best CD-Rs. The thing is, you can find generic CDRs made by TY for quite cheap. **So the point is *dont confuse BRAND NAME with MANUFACTURER** There are hundreds of brandnames but only a handful of manufacturers....
The professional standard CDRs are Mitsui Gold, which run about $1.40 each- at bswusa.com (which is a good price). Technically, I think the company is now Mame-E. (
http://www.mam-e.com). But not everyone believes that 'gold' discs are any better than 'green'.
I recommend this article:
http://www.mscience.com/faq53.html
and this:
http://www.itl.nist.gov/div895/gipwg/StabilityStudy.pdf
If you are going to do this, dont skimp on the CDRs you use. Research the different chemical processes used to make CDRs and choose which CDRs to buy- dont let them chose you because they are onsale at Circuit City - 50 for $5.00.
In 10 years, Ive only had one CDR that has 'flaked up' on me- where the layer of dye becomes pieces of flakes, making the disc useless.