Toro Titan
transmission or transaxle
The same as any riding mower. The following is a site which explains how the work: http://www.ehow.com/how-does_4689999_rideon-lawn-mower-work.html
Depends on the size of the lawn mostly. A push mower (or better yet a powered drive push mower) would have the best control in rough terrain, but if it is a large lawn a riding mower is better.
MTD
The best riding mower for hilly terrain is would be any kind of walk behind mower as you control it's movements, speed, and direction. However, if you have a large yard and want a riding mower newer LG mowers a good bet. An older option would be a Gravely Garden Tractor.
Can I do it myself, set the timing on my riding mower.
You probably have a bad bearing.
price
10W-30
Check the belt.
Place mower near street with FREE MOWER sign. That is the best way to remove the clutch/drive on this POS mower.