hey geeka- i have a pioneer DVD deck in mine and running a rearview camera. it's pretty cool. if you get the kenwood i think you also get the proximity lines.
as for the steering wheel controls yes it does work, if the HU offers a hardwired remote input. im using a perpheral (like PAC) in mine... but ck out this thread. if im doing another HU im going to use this metra control module.
Harness ...?