I'm looking to upgrade the head unit (6 disc w/ mp3) in my truck with a nice single din piece. i have a couple of questions for you guys if you'd like to clear some things up.

Can the factory overhead DVD system be wired to an aftermarket head unit? surely there are some RCA signal wires going to the back of the factory unit coming from the dvd system. i'd like to be able to choose that as an input so the dvd system audio can be pipped through the speakers.

I've looked up incorporating the factory sub into the aftermarket head unit. also read up on getting rid of the clunk when powering the system on/off. any other tips/advice would be good to get that working well. where do i get that smaller adapter harness?

Do any of our trucks have factory tweeters in the front? it looks like there is a space for some, but don't know if they are actually there.

Whats the best mount to use to get a nice flush finished result for a single din system?

Finally, i'm strongly considering the Pioneer DEH-P9400BH. My main qualities i'm looking for in a head unit are these:
-Bluetooth calls
-Bluetooth audio streaming
-Android friendly
-More than 3 equalizer adjustments
-Detailed display

Any help in any way would be great. I have a lot of experience installing/modifying stereo systems, but the newest car i've modified is a 2000.

Thanks in advance!!