O.k....lets see. I have never heard too much about glowshift gauges...so no input there. I can recommend the Cobalt series gauges from Autometer, they look awesome and are good gauges imo.
I would recommend EFI also, it will grow with your truck and mods. It is a custom tuning tool, not a tuner per say.
If you want a canned tuner, like I said earlier, the PPE would be my choice. My reasoning for staying away from the Predator is not due to my personal experience (so I won't list it) but enough reason for me to stay away from it. Also, the PPE Hot +2 iirc has a "fast learn feature" for the Alli.
S&B Intake, go for it. But the general consensus is the stock airbox will support up to 450-500 hp...and you can mod the stock airbox and help it breathe a bit better. Also a Green (or similar style) filter will flow a little more air.
MBRP exhaust, go for it. Had it on another truck with no issue.
Wastegate, its cheaper to go with the PPE boost valve...personally I would just make my own adjustable valve.
Hope that clears it up a bit.