Hey TeJay, I don't know much about air bags because I don't have any. I use the heaviest model (14,400 pounds) EAZ-Lift weight distribution hitch. I had an Edge M21 and the dealer gave it to me for cost (200 bucks) and they installed it. I guess he only used the heavy duty model because I didn't know anything about them and the technician said I really didn't need that stout of hitch. When I bought the NT, I had to do a little research because the height of the tongue was significantly different. Fortunately, the folks I bought the NT from set it up for me (the torque on the nuts is 260 pounds). I read the installation manual (on line) and it details adjusting the height of the hitch ball using something like 1/8th inch above the tongue for each 100 pounds of tongue weight. I may have to do that again because I just ordered a F250 6.7 L (looking ahead for maybe a bigger trailer).
The F150 has pulled the NT through the Texas hill country and the fairly long grades on I-10 just fine and with the eaz-lift wdh I haven't had much bouncing or sway . . . and of course when we decide to go on the road, the good old West Texas wind will be 20 - 30 miles per hour (being almost 0 on the days before and after we travel). One thing is I have had to make sure that I have enough weight in the front of end of mine to get the tongue weight up a little.
In Texas, they just use the weight submitted by the dealer when they register the trailer and it looks like they just take it off the sticker on the side of the trialer. So they matched.
On the mirrors, mine were the electric glass and heated (as are the towing mirrors I had put on). When I bought them, the guy told me that body shops are always looking at EBay for cheap parts. He called his distributor and got me the price of the mirrors (which turned out to be higher than the tow mirrors). I think it was like 373 for the driver side and 225 for the passenger side. I took pictures of them and had my sister put them on ebay for 250 and 150 dollars respectively. The were both sold (one to TN and one to MA) in five days. The buyer pays the shipping, but ebay taps you for about 12 percent so consider that when you price them. You can go to fordparts.com to check the current price for replacement mirrors and use that as your pricing guide. I would list them separately, not as a pair.