Matt, you'll probably need to get that body mount bolt from Toyota. It's a specialty bolt.
For your wheel question, I would say to get some 15x8 white wagon wheels - pretty common (see many pictures of mine in the link in my sig line) and allow you to run wider tires than the stock 15x5.5s. If you want to go to 16s you'll just have to find one out there that has the right backspacing and is the style you want. The only stock option is a split rim from Oz. I don't think I've ever seen a wagon wheel in a 16" size - might have to do some googling...