Going to change timing belt soon...
 

What exactly am I going to need to change this on a 04 Santa Fe GLS awd 2.7v6

I know I need...

Timing belt
Waterpump and gasket
Idle and tensioner pulleys

Do I need a new tensioner itself?

any other tools or parts i'm going to need?

You don't need to change the water pump but many people do because they are already going all the disassembly to change the timing belt. Yes, change the tensioner and idler pulley.

I'd also suggest changing the trans fluid, coolant, power steering fluid and brake fluid. Trans fluid and coolant should be changed every 30k miles. I change my power steering and brake fluid every 60k miles with the timing belt.

I know I didnt need to change the waterpump but we have over 135k miles so its due too.
Is just the pulleys ok to change or do I need to change the tensioner itself?

And does the trans have a screw on filter also? When I look up thans filters on a lot of site it shows a screw on type like an oil filter would be. Is this a mess up on the sites?

And where is the cabin air filter located and off hand do you know if the 04 GLS came with one.

I recommend replacing the tensioner at that mileage. It is cheap insurance to help your new belt last longer.

Usually you can find a timing belt replacement kit that includes T-Belt, idlers, pump, and tensioner at a discount. I just did mine with a Gates kit.

Good Luck!