Yes you can fit a car seat in there. High price or budget, a fair share will fit. Some have a better fit than others, key is getting one with a seat mold that will fit in the bucket. I've had the Eddie Bauer and the Costco toddler seats in the back of my 2+2 for 3 years now. Those are all front facing, not sure about rear facing but I think it should work. As far as safety, make sure you use the right belt clips like any seat belt and make sure you use the tether, I attach mine to one of the standard hooks in the trunk and keep it tight. I do not have a passenger when i take my little girl to pre-school so that helps with her leg room. She loves riding in the 'race car'.
..........._____.................... ....___/...........\____.......... ...l__..________..__\........alternate Z sig to avoid ........O...............O............hostile hosts .....DutchZX's 92 2+2........ ..........................................