A: Yes. This is actually the easiest setup since you will actually lift the mower using the bumper as the lift point.
A: It will. However, I recommend Instead of lifting under the front bumper you may need to adjust the forks to lift under the front suspension arms. I have had to make this adjustment in order to get my impact wrench under the deck and loosen the nuts that hold on the mower blades. When I lift at the front bumper I don't have enough clearance to use an impact wrench. I hope this helps.
A: Yes. It will work with this mower model.
A: 23" - 23.5"
A: After checking out the John Deere web site picture of the S120 it appears that it might work for that model if you adjust to lift under the steering arms. I would recommend attaching a front bumper to make it easier to lift the front of the mower.