Actually, beleive it or not, I did go over the documentation before asking and I am still not clear whether Ccleaner just erases things like temp files, etc. (like Windows' Disk cleanup does) or whether it "wipes" them. I used to use Acronis privacy suite in XP and it actually wiped this material.
(same for the remaining questions ..... It's a dangerous tool to use without absolute clarity, especially the registry cleaner)
Jeff