I will answer this as two separate questions...
1) How do I straighten the wheel? You don't unless you have private access to a quality alignment system equivalent to a Hunter branded equipment set.
2) How do I increase the steering effort? The only way to make it have more resistance would be to disable or impair the power steering (remove the pump belt perhaps or run tires with pressure reduced to very low levels? at any rate both bad ideas). Anyway, it sounds to me like the steering assist is working as designed. This is after all a "land yacht" not a sports car.