If you’re decent with hand tools, all the parts bolt off / bolt on. Tuners can email back and forth the required files once you buy their handheld devices.
I believe there’s a current sensor on the battery that could be bad, there’s also a fuse if I recall that can impact it. Orrrr it could be a bad ground /connection somewhere
I’d say 2k by the time you tune, block off egr and get the exhaust redone. Obliviously what brands and sources you choose can get it done at different costs and instead of blocking off egr you can unplug once tuned and save 100ish bucks but it’s all up to you
The oem fuel pump is more than sufficient for these trucks. Mine has 183k and hasn’t had any issues. I’ve found when parts fail, go back with oem on these trucks, anything else is a crap shoot