I'm considering replacing the basic head unit in my 2004 Vec SRi (full canbus I think - wheels to adjust volume on steering wheel?) and have a couple of questions.

1) Will I lose the use of the OBC with an Alpine head unit fitted? If not, how will I get it to work?

2) What do I need to get to complete the installation?

3) Do I need to tech2 my old head unit from the car if I intend to replace it when I come to sell the car?

4) How much would I be looking at to get it installed for me?

Thanks for any help you can give!