07 nnbs 2500, new truck problems (long and detailed)

Picked up the truck on Friday 2/13, took it for a test drive looked it over, returning I told sales guy I wanted a few things taken care of…
Service airbag light was on, and the doors were squawking.
They took it in the shop while sales guy and I chatted and looked over paperwork. He disappeared and came back and told me they greased the doors and that they couldn’t do anything about the service air bag light there at the shop, he would talk to the original sales guy that I worked with and I could work something out with him to take it to a real Chevrolet dealer and get it taken care of.
I didn’t think much of it but later talked with an auto tech buddy and he said that a lot of the better made DTC computers can removed the light (his was a MAC tools one) and that he’d be surprised if there full time mechanic didn’t have the right one to do it.
So I left and about 20 miles down the road my low tire pressure light came on. I drove another few miles and stopped off for fuel, checked the tires with a gauge and all 4 were even at 56psi. texted the sales guy the next day and he said that the tires were bigger so they wouldn’t read right and the system light would stay on. Then I remembered my brothers new truck and that he had to buy the fancy valvestem sensors for the aftermarket wheels so that he wouldn’t have this problem.

Quick Q on the side,
So when I buy the sensors and have them put in, I then go to a GM dealer and they can reflash or reset the TPMS to work and correct the tire size in the computer so my speedo/odo will be accurate again?
Calculated my mpgs based off of fuel that I put in the tank and the trip meter (said 288 miles but was actually 310 miles). To me that’s a significant difference and I’d like to get it fixed.

Later that night I tried to use my wiper wash and nothing came out. DAMN! Another 200 miles to drive in the dark snowing and no wiper fluid. Trip was interesting. 3 days later when the temp warmed up from -9* to +18* the wiper fluid defrosted and they started working again, the next stuff I buy will be the -25* rating!

On 2/14, i pulled onto one of our seasonal use roads (gravel/stonedust base) thats gets plowed but is still slippery and has snow on it, i put truck in 4wd and started to take off.around 15-20mph, there is a really strong vibration that rattles the whole truck. possibly a light metal/scraping noise, hard to tell with the exhaust rumble. i mentioned it to sales guys and he claimed trucks shouldnt be driven at high speed on dry pavement. i told him this isnt high speed nor dry pavement, and ive owned and driven plenty of 4wd vehicles and have never really felt this. My brother was thinking a ujoint from what i told him but was too busy to drive it. it goes away completely in 2wd, and shows up everytime in 4wd. dunno whats up with it but maybe i can take a video later and share it. any suggestions?

On 2/16 I left my grandparents house after dark and tried turning my high beams on… it took me flicking the arm 3 or 4 tries before they turned on, then I tried to switch back to lows and again it took a few tries, after I got out of the city I tried to switch again and it just wouldn’t change. I drove home and when I shut the truck off and manually shut tried to shut the lights off it wouldn’t work. I went inside for 10 minutes to see if it was just the timer setting thing but it never turned off. I changed into some warmer clothes (-30s after windchill) and went out to start playing around. Checked my fuse panels and started to look around. Dad told me to grab the owners manual so we could decipher some abbreviations and wouldn’t ya know, those fuckers at the dealership didn’t even give me one! I was pissed! I grabbed my dads from his truck (04 2500) and we made due. We pulled the headlamp relay and low beam fuses but no change, and it wasn’t until my dad pulled the high beam fuses that the lights finally went out. I still couldn’t believe that even a used car dealership would sell a rig without an owners manual. They have so much important info for people who DIY stuff. I texted the sales guy that I want a book and he said he’d “see what he could do”. My ass, he better find one or steal it from another truck.
Next morning I stopped at Advanced Auto Parts and picked up a mixed pack of fuses and the cheap little fuse tester that comes with them. All the old fuses put back in and they all lit up the light. Swapped them all out with brand new ones and they still all lit up but the headlights still stayed on. I asked if I could have a new headlamp relay to try swapping in and test it. They gave me one but it didn’t change anything…. Grrrrr

Drove up to my girlfriends house and started to play around with the fuses again. It was only the bottom set of lights (apparently the hi beams?) that stayed on when all the fuses were placed back in. I pulled the hi beam L and R fuses and the top set (low beams?) came on. I played with my switch and ta daaaa, I was able to shut the lights off. At least now I could drive the 400 miles in the dark and not worry about blinding anybody and I could shut them off everytime I shut the truck off. The hi/lo toggle didn’t have any effect on the lights. When I tried to switch the his on the lows stayed on and did not flicker or go off. But the switch would let me shut the lows off, set it on auto, turn the marker lights on, and then actually turn them on.
Anybody have any ideas? I am taking it back to the dealer on Saturday to have them look at it, ive been told possible bad switch? Either the high low toggle or the actual light on/off one. I am kinda stumped and haven’t been able to find much online.

Then this morning 2/19/15, (another cold ass night/morning in Pittsburgh 8*F and -15* windchills) I went out to start the ol girl up and the CEL light came on and gave me a “crank no start” condition. I was ready to cry, lol (my f250 6.0 was notorious for crank no starts and I could never fix it myself). But logic took over and my days of gasoline engines started to come back to me. I listened for a fuel pump hum but couldn’t really tell if I was noticing anything (damn wind was blowing and hard to hear). I decided to swap the A/C compressor relay for the fuel pump relay (haha A/C in negative temps, wont be needing that) and voila! She fired right up! I was very happy to not have to walk to work. Ive been walking 6 miles everyday to this job since December 1st.

So I guess my only real questions I still need answered are the TPMS sensors, 4wd vibes, and if anybody has any similar issues with the head lights so I can maybe point the dealer in the right direction and not waste an entire day Saturday waiting around for a diagnosis.

Thanks y’all!