The hyd tank is on the right side- as sitting on the machine. There should be a plug under the tank for draining purposes. If you take off the top of the tank (with the hoses going to it)- that's where the hyd. filter is ( I'd replace that also). Unit should take between 5 & 10 gallons.

As far as the brakes- it's a fairly complicated system. There's a master cyl connected to your brake pedal- which feeds 2 circuits- the brake circuit & the inching circuit. The inching circuit puts the trans in neutral when the brakes are applied.

The brake circuit goes from the master cyl., thru a remote brake power booster assy, then to inboard reverse acting disc brakes inside the rear housing. If your brake pedal is high & rock hard, I would suspect your discs are wet from either brake fluid or trans fluid- Either way the disc assy's will have to be removed for service. You will need some serious mechanical ability & a wide variety of tools to attempt to get into the brakes. The parts for the brakes are available but get quite pricey.