If you have a true walking foot, which is actually a generic term for alternating presser feet, the feet are in two parts. The middle part of the foot is where the needle goes through, and the rest of the foot is attached to another shaft which goes up when the other part of the foot goes down, hence alternating. You can't remove the walking foot, or the machine won't feed correctly. Welting is made with a welt foot. If you are trying to make welting with a presser foot, it will not work.
As far as the stitch length question, the machine may be set to the biggest stitch possible and can only turn one way with the hand wheel. You also may be depressing the wrong button. One of the buttons on the bed is for re-setting the safety clutch.
No one lives forever, the trick is creating something that will.