Seems like you have 4 options instead of 3.
Turning your actic into "conditioned space" wouldn't save you any money. I would opt for increasing the ventilation and adding insulation. You can work around the soffit vents by adding baffles to avoid blocking the air flow. Chances are that you may need to add a few more soffit vents. Do you have gable vents as well? If you do, then don't put in ridge vents.
If you have asphalt shingles I think you would void any warranty by using the roof spray foam.
There's more to this than the points I've mentioned.