I recently ordered a whole door kit on summit from precision, all worked and fit fine, pricing seemed better the the team site, but if they are a sponsor I would go there
u shaped thing goes on the oil pan. the bracket with the hole in it looks like it was for a hood switch or a maybe an ac line. not sure on the rectangle one.
just did this to my 1992 briarwood, used a computstar from amazon for 150 bucks, works great even down the street. Wiring was not hard at all, but you need the door relay add on wiring which was like 7 bucks on eBay to change the door locks to proper polarity to function. Remote start as well...