according to 'Crutchfield' in the dash and behind the seat the speakers are 4x6. The doors are 6.5" but a aftermarket speaker will not fit without doing some modifications to the door. I would assume you would need to make a bracket that protrudes the speaker away from the door for the glass clearance and you will have to probably drill new mounting holes as well.
earmarkcaraudio.com Can make some MDF adapter rings pretty cheap there in Plano. As far as good speakers I would suggest just going to the local audio shops and listen to as many sets as you can and choose what sounds best to you.