fronts go with the 6.5" with mdf mounts "its easy" and alot stronger than the stock plastic mount.
but for the rear im not sure. i re made the parcel shelf for 6x9s my self, but this is alot of work and if i could do it again i would really consider 6.5" for the back. but im not to sure about fitting them to the stock mounts. u should do a search because i think 6.5" in the back has been covered b4. and when it comes to depth u should be fine, but u may have a taller battery than me so u should check the gap with a measuring tape. think the gap between the battery and the metal shelf + 10mm for depth.
if u want to re make the parcel shelf use the original parcel shelf as a templet and what i did was use foam bed underlay on the underside for a nice fit. u will need mdf, carpet, nuts and bolts, jig saw, drill, staple gun, power sander (belt if possible) and a router will come in handy. also if u have child restraints u will have to make allowances for them.
pm me if u have any questions and i will do a proper right up