A:AnswerDo like I did: go to Crutchfield's (http://www.crutchfield.com/) to find out which units will fit your particular car. I did not buy from them, but it was a valuable resource to find out which stereo units would fit my car. They have helpful experienced sales people you can call and discuss your needs.
I checked Crutchfield's for your car, and they reference 123 car stereos that will fit your sedan. Lots of AM/FM and AM/FM/CD units, but I didn't see any with cassette when I shopped for my replacement unit.
For getting my new unit installed, my local Best Buy offered Geek Squad installation services, which were fast, expertly done and were the most inexpensive after shopping around in town.
A:AnswerDo like I did -- give your local Geek Squad a call, tell them the details about your car and new unit and speakers, and they'll be able to advise you about what it will cost and to ensure they have all the parts needed for a proper installation. They were significantly cheaper than any other business in my town, and did excellent work.