Dirk,
I appreciate you efforts to fix your lift. Let's assume that you are loosing TRANSMISSION oil. That could explain your leak and why you can climb a hill half way. The transmission dip stick is between your drive tires. You will actually have to bend it to get it pulled out easy. Insert a small funnel in the tube and add Dextron until it is to the fullmark NOT running. This should cover your transmission.
On the CY40B (big tires) the master cylinder is below the starter. Probably the same here. You will have a heck of a tome getting the cap off. Chisel it off if you need to- you need to get the system bled to determine if the wheels lock up. Use a 1/4" six point wrench if you have one to crack both wheel bleeders at the diff housing. Use brakefluid in a new oilsquirt can with 8" of vacuum hose attached and hook it to the left bleeder. Pump until you get clean fluid out of the right bleeder. Close the right bleeder and loosen the inching bleeder (if still equipped) on the top of the transmission. Pump again, then close. Now pump one last time while watching the master cylinder. It should start to fill. Close the bleeder and you may have brakes.
I am pretty sure your lifting problem is an adjustment. Loosen the 2 Allen head bolts that at the bottom of your hydraulic bracket on the lower portion of your steering column slightly. Gently tap them upward about a 1/4" and retighten. This should get her lifting just great.
Steve