contact me on AIM, i can answer all your questions about that stuff.
DVDR games (ISOs) are full DVD size while DVDRips are cut down versions withouth cinematics, music, or other stuff. DVD-Rips fit on CDRs.
HDLoader is NOT going to work on a PSTwo (slim PS2) since there is no HD.
Depending on what mod you have, it could wear down your PS2 laser. Early mods for the slim PSTwo basically kill the console, so beware of those. Newer mods are good, but all mods will use up lasers at least 2x faster since DVDRs reflect less than half as much as pressed DVDs.
To back up CD games, use Alcohol, for DVD games use Recordnow Max (i think thats the name).
answered your questions?