I just got my M45S Tech/Journey/Aero this last Saturday and it is the best.
Yes, the DVD drive is in the center console.
Not sure about the steps to integrate an aftermarket monitor for the back but check out
zerothread?id=146336 for some pics of some built in head rest monitors. Maybe contact the poster for what was done.
As for seeing video on front NAV while driving, see
zerothread?id=139095 for some info. Maybe not the best idea but I know I'll have to look into it if Apple ever fixes the new Video IPOD to output video while in normal audio mode. Maybe I couldn't control the IPOD from the car/steering controls but I would like to see the current song info.
The M with all your add-ons is all that. I've found the NAV screen to much more useful than my 2004 FX35. There's more info to see on the screen than just maps. Remember that the M35 has the same engine as the G35 and the car is ~600lbs heavier so the lb/hp ratio goes up. But it's still got the giddyup to go.
Enjoy!