I have an E36, not sure if I can help much at the mo, as it's continously being redesigned, however to answer your questions
1- where did you put your LCD ? Are you comfortable using it at its current location ? - It's on top of the dash at the mo (pioneer WD6010 quick release) . No looking to get a proper VGA one.
2- did you relocate any of HU/climate controls/OBC(full) ? if yes, which one(s) to where ? - No, but am looking to move the climate control down to the bottom, however then need to find a home for my head unit
3- where do you keep your case? - in the boot, its a compaq EN SFF, it's connected to the back of the seats with video brackets
4- Are you using your stock battery or replaced it ? yes stock battery, I have a 6 cylinder so it's bigger than the average anyway (plus it's at the back )
5- what power supply did you select ? currently using an inverter, however want to change to a DC-DC, but will have to change the PC as the compaq will not take a standard ATX PSU.
Don't know if any of that helps.
Sorry no pics as of yet either