you can If it's an older version. on the new versions you can't
no unless u buy them throw ps3 online ore get a ps3 jailbreak chip or usb drive
If it's a new PS3, no. If it's one of the originals and it's system hasn't been updated, yes. Fortunately, PS2 systems can be picked up for roughly $50 these days (albeit used or refurbished) so if you want PS2 capability as well, it's not all that expensive to have the PS2 as well.
how aboot this?http://www.tech-faq.com/can-you-play-ps2-games-on-ps3.html L