The safety neutral switch is inside the center console in front of the shifter. You could also check grounds, or try hitting the starter with something when someone tries cranking it and that will diagnose the starter issue.
The common swap is a c4 zr1 wheel which is a 9.5" wide front with a 275-40-17 tire. I believe this rubs a little at full lock but have had no issues running them on my truck