I was looking at high end HU reviews including AVIC, Kenwood DNX, Clarion NX series and many were not great. Most people seeking high end are wanting Nav, Audio , Video, Sat Sirius.
I came across more than a couple of installs of IPAD (which perfectly implements many of the elements with a never ending stream of improvements and accessories.
The problem is I live in Fla and would have to remove the IPAD at every stop for fear of break in, even if built in (someone would bust a window and take a crowbar to the dash.;-(

Consequently I am considering installing an upgraded head unit (single DIN) and add a built in slot in front of it for the IPAD.
I would use the head unit for quick trips and insert the IPAD for longer trips.

1.I believe the head unit would need to stream BT in from the IPAD, although I guess it could be USB or even aux input 3.5mm. Any difference on audio quality based on the input?
2. I need the head unit to take the stereo and allow separation of front and rear and L&R .
3. Any recommendations on a reasonably low cost head unit, with BT and USB that would work for day to day and as an audio processor behind the IPAD
4. I have a 5 channel amp and Boston Acoustics Components with crossovers and single 10 sub.
5. Ultimately would want to add rear video on a separate stream from the IPAD while still using nav or playing music (or both).

I am obviously new at building this but an electrical engineer and engaged in technology.

One last thing, has anyone seen an IPAD lock box? I have a few reasonable places below the main seats or under and behind the rear seats where I can lock it up if it is not reasonable to carry it around. I can weld one from scratch but would rather purchase.

Thanks in advance