I added the Teraflex JL Alpha HD hinged spare tire carrier kit to my existing Teraflex Alpha adjustable spare tire mount. It requires removing the Alpha and reinstalling it. Solid piece of hardware and great customer service from @TeraFlex.
I have the 2.5 Metalcloak with dual rate springs and Rockport long travel shocks. It rides better than stock with no swaying. I haven't had a Teraflex kit, but wouldn't be surprised if they are fantastic, too.
I just did this. I was trying to keep my stock wheels. After researching wheels/tires/lift, I went with a Metalcloak 2.5" lift. In order to keep the stock wheels, I was going to have to either get 2" spacers or buy new wheels. In the end, I opted for new wheels. It's really a personal choice...
To be honest, I have no idea. Power Tank has a table that gives approximated usage.
I got the 10 lb. tank and have 315/70/17 tires. I'll be using a Morrflate system to air all four tires at once.