Personally I can't remember what my rigger has for AOA. I believe I'm somewhere around 3 degrees. My Front sponson is 13.5" on a 34" hull and has 5" of the 3 degree AOA.

The more angle of attack will give higher speeds but increased chance of lifting off the water. Lower increased AOA will provide great stability.
Lowering the Strut will artificially lower your AOA. Raising or lifting the strut will artificially increase your AOA. This works best on riggers with no rear ride pads (sponsons)

I would not offset the drive. When you trim out the boat properly you will not really notice prop walk. I personally have never had a problem with prop walk. Usually my hardest problem to solve is prop bounce. (for the smaller riggers)

Ryan