Running low on fluid isn't good hopefully you didn't damage anything. I would change the oil in the engine and the hydraulic fluid.
Take the filter off and go to napa, they should be able to find something. No way to know what your machine has on it. I would guess that no two are exactly alike.
Wheel spacers: as light as it is I don't thing it will hurt it. Spacers do increase the load on the wheel motor bearings.
