so you got issues starting, running and all the electrial stuff is going googlie eyed on you. guess what? it's either your alternator or battery. most likely it's the battery.
head over to your autozone (hey, they are more then just for O2's) and pick up a Duralast 49-DL
. Secret about car batteries: there's only 3 manufactures and all are about the same; Duralast is made by Johnson Control which also makes Diehard, Interstate and Optima . don't spring for anything more like Optimas unless you are going to compete in audio show which then you'll need special batteries but for everyday Joe, Dick and Bob, the Duralast is your winner. And at about $65 (i think.. could be $67 but not over $100) plus tax, it's the winner by a HUGE margin.
save some ducks and take yourself out to a good dinner with the $65 you just saved then going to a dealer for a battery.