A good place to check fit is on the
Crutchfield website. In the Disco door, you are kina limited as to which speaker you can use because of the depth you have to work with. I know Kenwood and Infinty have some nice model's avaliable for sure - am I'm sure other makes do too...
Install is simple. It's four screws that hold the trim, and speaker in place. Once out, there are two wires, a postive and negitive. It's basically a "plug-and-play" set-up.
I would look at a nice 2-way speaker. Anything out there, really, will sound better then the stockers...I like
Infinty and
Boston Acoustics speakers, but that's personal preferance.
The rears are up to you. The stock rears will work fine, even with replacing the fronts. But, they too are a "cheap" OEM speaker. The sound quality will be a lot more "awesome" with a good set of aftermarket speakers. But again, it's not nessassary...