[JJ. in B.C.]

This wiring diagram for the MF35 should help you out

 

[JJ. in B.C.]

Jon, i believe workshop manuals are still available from your AGCO/MF dealer.
When the Thermostart is activated it meters a small amount of fuel from a small holding cylinder in the "leak off" return line from the injector pump, this is then ignited by the heating element and drawn into the manifold, your thermostart sounds like it is likely burnt out and needs replacing.
The hydraulic filler is located to the left of the main gear shifter, a large plug, the dip stick is by your right heel when sitting on tractor, this is a common reservoir for the hyd/trans/diff.
If your 35 has the dual clutch the 3pt hitch will operate independently of the PTO when the clutch pedal is released.

 

[JJ. in B.C.]

Unless you are able to locate a donor tractor with all the PAS parts intact retrofitting the original system would be cost prohibitive, thats if you can even find them, i don't think they are still available from MF and if they were it would probably be cheaper to buy another tractor with PS, the transmission top would have to be changed to one with the PS gear cast into it as would the gears and steering shafts, then the pump fitted to the Perkins engine and all the lines. If you feel you really have to have PS some type of aftermarket add-on would be the way to go.