Here's a link with instructions and copies of shop manual.
http://www.vwdieselparts.com/tbelt.htm Can I just slip off the old belt, install the new tensioner, and slip on the new belt?
No. You need to lock the cam with special tool (can be improvised with a flat peice of metal) and you need to lock the injection pump with a special tool (11 mm deepwell socket may work depending on brand)
Is it possible for the cam wheel to spin once the old belt is off?
The bolt in the center should be slightly loosened, and pull the pulley off the cam and then allow the pulley to spin on the cam while the cam is locked. Dont forget to tighten the bolt later.
What weight/brand of oil should I use in the engine?
I like 5w-40 synthetic
Do I need to use any type of sealer on the water pump gasket?
Matter of preference. I like silicone by itself with no gasket.
I'm an aircooled guy and not used to this liquid coolant stuff.
Me too! Dont ya hate it when that green stuff leaks out and you get it on your skin, or worse yet you slip in it and fall on your @$$!
Any other tips/issues I should watch out for?
Check for leaks at IP seal, cam seal, front main, intermediate shaft. Dont loosen the crank pulley bolt unless you have to.