The 2 10's will be enough for this system. I had a pair of mtx 10's in the primera with my 2 sets of compts and it was balanced enough for me
you can use and of the poineer dvd decks, 2300,3300,4300DVD
i have the 4300DVD and it works exceptionally well. Also used the 2300DVD in alot of sq based installs just like the one you describe and it also works well. The decks also have very good built in high pass and low pass crossovers and graphic eq's so no additional processing is necessary.
IMHO the 4 doors with adequate matting installed are enough, mounting mids on the backdash also will be overkill and mess with your front staging.
If you want you can give me a call and i'll help you through the system or even install it for you if you wish.