"Backing up" questions (just a couple!)

Don't slay me for this folks but I admit, I've only backed up my files twice in my life (once in Jan and once the other day).

I selected certain files (writings, photos, farm records) and put them on a CD. That's what I did in January, too.

When I put in the Januar CD to view it, how come I can't "explore" which files are on there? It just gives me the name of the CD I gave it. Is there some way to save all these files to a backup CD and be able to view the list of files on it?

I was hoping I could explore the CD and choose a file to put back in my Computer (should I ever need to) and not put them all back in. Or does it work that way?

Also, if I reload the January backup (for example) does it delete my files that I've added to since January ?

In other words, if I've written a story of 4 chapters and saved that on a backup...then over the next few months I increased it to 9 chapters...then when I need to use my backup CD (because a different file is gone), will my January backup take away my 9 chapters file and replace it with the 4 chapter file, or will it see that that particular file is there and not mess with it?

Am I making any sense?