Sounds like the truck is going to need a bit of work. I do not think that the 2007 model's had a tire pressure system, but in canada it may have. (I'm from the US) It could be that one of the sensors in the tire had the battery die. They are not to difficult to have repaired.
The rear brakes should be gone through completely, with both wheel cylinders being rebuilt / replaced, and new hardware and shoes, and maybe even new drums. If you are going to have the system completely apart to do the wheel cylinders, you might as well get to all of it.
I would recommend that you take a real good look under the truck for any signs of rust before you sink too much money into it. Also check out the radiator core support. No matter how clean the truck looks, this is a known problem area for these trucks.
If the airbag light is on, get it checked on a scanner. You can get a scanner for a decent price that will serve you for a long time. Things can get expensive to replace with the airbag system.
The truck does look like a nice find though.