To start off with the speaker that are fitted in the rear are 6.5", i suggest in replacement that some sort of coaxial speaker would be the best type to replace the standards! NB: to make sure the magnets on the replacement speakers aren't too big as there isn't much room when fitted and you don't want them to rub onto the body of the car!

The sort of tools you will need:

Spanners, screw drivers, drill and socket set (with Torx ends)!

I will try to keep this simple (and not mumble on to much)