I use the chains attached at the lift arm and bottom of the top link at the tractor to control the height at the front of the bush hog when using my Yanmar because I could never get it adjusted properly after raising and lowering without stopping and looking. It was always too high or low so I put the chains on and just dropped the lift arms down so they float. All the weight is carried on the tail wheel and the chains that are attached to the top link attachment point on the tractor. That keeps everything floating till I am ready to lift it. I can keep my top link loose so the back of the bush hog will lift without binding on the top link. I can go thru deep ditches, back up 30 degree slopes like on my pond dike and not bind anything and the chains keep it at the exact height that I want. You can buy them at farm supplies like Atwoods and tractor supply. You also dont want the BH front skids dragging on the ground. NOT only does it leave ugly marks in your pasture, but it wears out the skids very quickly.
Tail wheel should always be adjusted higher in back than in front for heavy hogging to allow the trash to clear easier. It should never be lower in back than the front in any case. Level would be ok if you wanted to really shred the material, but it is going to cost you some extra power and fuel to turn in that way as you are chopping and rechopping the forage material.