You didn't specify what years you are looking at, but I have 2 Toyota Tundras, the first one is the first generation a 2006 model with the 4.7L V8 5 speed automatic transmission with just shy of 120,000 miles on it, it was used for considerable amounts of towing cross country of a 20 foot travel trailer, so it has all the towing accessories to include firestone airbags in the rear. It runs and drives great as if its still new with over 100k miles on it. My 2nd Toyota Tundra is a 2008 Double Cab 4x4 with the 5.7L V8 and the 6 speed automatic transmission. I have 64,600 miles on it and haven't had a single problem with it either. I've driven both considerably on long trips, the 2006 averages around 14mpg in town and around 20mpg on the highway. The 2008 gets about 15mpg in town and around 22mpg on the highway. The problem you are going to find with fuel economy is if you have to use ethanol fuel subtract about 2-3mpg from the numbers as the ethanol is junk and engines don't like to burn it. You will also find yourself hitting the throttle pretty hard for fun LOL.
Engine longitivity is hard to say because you don't know how the vehicle might have been cared for by the previous owner(s). I'm a member of a toyota tundra forum and see some pretty high mileage on the first generation tundras with no major failures some are reporting close to 300,000 miles on first generation tundras with no major issues. There are a few owner's of the 2nd generation tundras reporting close to 200,000 miles with no major issues as well.
Brake systems are like any other truck, its a truck it takes longer to stop, however having both a 1st and 2nd generation tundra I can say the brakes do very well considering the weights of the trucks. Both trucks have anti-lock brakes. The 2nd generation has traction control, stability control which I find annoying most times.
The 2nd generation Tundra was released in 2007, all models prior to 2007 are generation 1.
Engine options for the 1st generation was the 4.0L V6, and the 4.7L V8.
Engine options for the 2nd generation was the 4.0L V6, and up till 2009 the 4.7L V8, then in late 2009 the 4.7L was dropped and a 4.6L V8 took its place, and then the largest 5.7L V8 engine.
NOTE: The 4.7L V8's had timing belts which needed replaced around every 60,000 miles. The 4.6L and the 5.7L V8's are timing chains.
Fuel economy with the V8's seems to be about par with the V6 engines. Sometimes the V8's getting better fuel economy just because they're not working as hard to move the truck as the V6 engines would have to.
The Tundra is available in 2WD or Part Time 4WD options.
You can get regular, double, or crew cab versions in either the 2WD or 4WD configuration.
You can get Base, SR-5, Limited, and Platinum editions, along with the TRD Offroad Package as well.
Hope this helps.
2 Toyota Tundra Owner.