Advice needed

posting this for a TW mod. I thought the '07 had a water pump issue..or was that '08? Anyone here with an 07'ish that can chime in?

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A friend is trading in his Tundra and I could probably get a stellar deal if I bought it from him.

2007 Tundra, double cab, 5.7 L, 70,000 miles. The truck is immaculate. Within the year, I would probably buy new tires, camper shell, and stereo/backup camera.

My Tacoma is 2007 double cab, SR5, 70,000 miles.
Good:

• mechanically perfect (except as noted below)
• running boards
• clean interior
• nice stereo with backup camera
• camper shell
• newish tires
• seat covers
• heavy duty rear bumper

Bad stuff

• big dent in driver's side, rear quarter panel
• assorted scratches all over
• cracked windshield
• heavy duty rear bumper isn't exactly safe
• 14 MPG (not sure why)
• sounds like it is hanging in 4th gear on the highway (but the RPMs say it is in 5th)
• some leakage around the top cover on the engine
• add coolant every 2 years
• AC works but struggles a little when idling

It would probably pass a mechanic's inspection, but I know there are some issues with it.

On the financial side, I can purchase my friends truck for $14,000, and hopefully sell mine for $17,000.

$14,000 Tundra
$1000 Tires
$1200 Stereo/camera
$2200 Camper shell
$1500 tax
=$19,900 total
-$17000 private party sale of Tacoma
=$2900 out of pocket expenses

I'd like the Tundra. It has better gas mileage, much better condition, more interior space (I have 3 young boys,) more cargo space (but not needed,) OEM rear bumper makes it safer, more comfortable front seats, and it is something different.

Here are my questions:
1. Would you do it and why?
2. Am I dreaming to think I can get $17000 for my Tacoma?
3. Is this worth the hassle? I'd have to get a car loan, sell my old truck, buy camper shell, tires, register truck, pay taxes, and spend several weekends installing a stereo/camera.
4. Do you know of any issues with the 2007 Tundra? I'd rather not buy a truck and have the engine blow. My friend has babied this truck and never towed with it, never off-roaded, etc...but I don't know how many more miles I can expect without major maintenance or expense