yes they did take out a chip that allows u to play PS2/PS1 games they replaced it with software so u cant play as many PS2/PS1games but it will change in the future

yes u can replace the PS3s hard drive with a bigger one and it is 100% legal

the PS3 is a very quiet machine

yes their is something that helps find cures its called folding at home and all u need is a internet connection for that

the 80gb PS3 is weighs the same as the 60 and looks the same id say 3-5 pounds

alot of PS2/PS1 games will work but not all and the PS3 upscales the games so they look better

hope this helps