Like the look, agree about the bathroom too large unless your 600lbs. I would make more spacing around heavy machinery. Plywood on walls is OK, but it should have Type X sheetrock; may lower insurance cost. Personally I would go 2x6 studs, 16"c/sheetock for shelving strength, skipping the plywood. Lastly I would find an empty paved lot, lay out the entire garage including walls,car dimensions, equipment dimensions with chalk lines, after it is laid out check all spacing/elbow room.
"Regarding the site work, the plan is for a lot of fill." Best be damn careful to fill/compact properly. You might need piles or piers