Being it's a 1500 there's no trans temp gauge. I'd recommend a replacement pan with a temp port and an aftermarket gauge on the dash. You would also gain some extra fluid capacity. I believe they make them for the 4L60e that you should have. I might would even look into a larger cooler than the OE one. The "HD" one that's on there isn't much. I only say that because I had a 2500HD with the 6.0 and the stock cooler was tiny.
I would flush the coolant and replace rear end gear oil as well.
Save you $$$ on the CAI, just replace the OE filter.