A 5 point carseat is the best. They are pricier, but worth the piece of mind. Just make sure to take it in to your local fire department or police station after installation to make sure it is in right...they are difficult to get in correctly and tight enough. Once ours was in, it rarely came out for this very reason. We had a carseat very similar to this one:
http://www.amazon.com/exec/obidos/tg...=glance&s=baby
As for strollers, I never liked the combo ones because they are so bulky; I preferred smaller ones that would manuever and not block up a bunch of space.
It all boils down to personal taste, really. If you have a limited income, I would really try to get the safer carseat and a smaller, less bulky stroller. If you need to carry something with the stroller, you can always bring a diaper bag.