I used this monitor and camera setup in my mom's van so i didnt have to add a screen and keep a mostly factory look. but if you want that screen in your car, more power to you!
I recently did a nexus 7 install in my buddy's e46 bmw. We used This clarion eq. you just have to use a 3.5mm(from headphone of ipad) to rca converter(input of eq) along the lines of this, wire it up and the rca's go out to your speakers! thats how we did it
Im almost there saving up for that digital guard dawg system. I really want it as well, plus....push start haha. plus, most aftermarket remote start system remotes look ghetto(imo) but the guard dog one looks really nice and factory
but good luck man! keep us updated!