How many times can you record to a CD-RW?

According to Sony, on a CD-RW disc you can record anywhere from 500 to 1,000 times depending on record speed. The slower the record speed, the fewer passes.

Is there a CD-R that's not green or blue on the bottom? I need one that's silver, like a replicated disc.

Yes. They're called "diamond bottom" discs.

Diamond bottom discs, often referred to as TruSilver or platinum CDs, are silver on the bottom. They look very similar to the professionally replicated CD-ROMs you get when you buy a music CD or piece of software.

While they may look better, burn times tend to be slower than standard, color CD-Rs. The Spin-X diamond bottom CD-Rs have a burn rate of 48x versus 52x. In addition, diamond bottom CD-R discs often cost a few cents more than the standard color CD-Rs.

What's the difference between CD-R and CD-RW?

CD-R is a recordable, write-once disc.

CD-RW is a recordable disc that you can write over many times. RW stands for rewritable.

CD+R and CD-RAM do not exist.