A good fluid to use is regular hy/trans. You can get it at most farmers co-ops.
The filter is a screen tube behind your right foot board covered by a square metal plate. You are probably better off leaving the filter where it is unless you get quite a few shavings when you drain the oil. It's a booger to get lined back up with the suction line when you go to put it back in. Those screens are good at lasting a good while.
There is a fill overflow plug by your left foot. Pour oil in till it comes out of that hole and put the plug back in. It shouldnt hold more than a few gallons.That should do ya.