The gerotor motor looks like it will work. The RPM range is there. Working pressure is a tad lower than ideal but I'd say it's a go.
The pump in the schematic is the symbol for a hydrostat (simplified). The Sunstrand that you picked out looks like a perfect fit. Make sure the counter-clockwise input rotation will work with the engine output. See if you can find the cut-sheet and/or manual for the pump.
I'll spec out the valves for you. I plan on designing the manifolds for the valves. Most will be cartridge valves. They are inexpensive and easy to maintain. www.sunhydraulics.com
Because of the lower pressures we're working with, <3000 PSI, we can use aluminum body components. Brings the weight down.
Just let me know what symbols you have questions about.
I've come up with some ideas for dynamic hydraulic braking I'll include in the next schematic.