Welcome to the Scene! Lets see a few pics also.
The 17" wheels should work, I know quite a few are running them here......I'm more of a stock type guy myself, although 15" are nice for me!
Here's a pic of the horn.......the bumper & grille are removed on my truck here also......as if you couldn't tell!
Some of the trucks, like the LX package trucks, had the chime thing in them.....not sure if it chimed when the lights were left on though......thought it was just for the key in the ignition and the door was opened.....maybe I'm wrong here.
Look up Mazdizzle's post on his truck he just put together......he did a tweed wrap on a lot of the interior panels, including the dash......it looks great! He did a perfect job on it, and it can give you some ideas for the interior.
Welcome man!