CD burning questions

[Keith Whaley]

I think the answer I'm looking for is unambiguous, and ought to be dead 
simple, but I'll ask anyhow... <grin>

When I take a fresh [new] CD, mount it on my desktop, and load a number 
of items onto it for safekeeping... and then "burn it", does that 
essentially lock the CD for any future adding of data?

I'm talking about CD-RW discs, by the way, written to by my Panasonic 
CD-RW drive...

I'm way too busy to research it right now, and since seeing "DVD 
Burning" on the list, it prompted my question.
I have time enough to ask, but not time enough to do a lot of fooling 
around testing this and that configuration, etc., so I thought I'd ask 
the gurus here...

I've used that drive and CDs for backing up my HD many times in the 
past, but I just blindly follow what Retrospect tells me to do. Insert 
disc 1-Storage Set A, or 7- or whatever. And soon enough it's all done 
and I go my happy way, no more educated than when I began!  <g>

Just thought of question #2:

With respect to CD-Rs, once you perform one (the first) write-to 
exercise, is that IT?
You have this 650+ mb capacity, and only need some 25 or 30 mb, let's 
say, but once burned, that effectively "locks" the disc and that's it 
for THAT disc?
You can't fill up the bag? Use it to carry around one marble, and be 
glad you had a bag to carry it in?  <g>

Many thanks,

keith whaley