your strategy for point #3 above (downwind without spin) would likely vary

In your situation, it would seem that you were more concerned with keeping the boat manageable (by dropping the spin) rather than maximum VMG. In that case, I'd keep some traveler in for the "reserve" should a sudden puff or something pick the boat up and you need to reduce power (in combination with a heading change). Weight should be all the way on the back of the bus, and boards up somewhat depending on conditions. The strategy would be to reduce lift and avoid knockdowns.

If it's really honking, some advise to sheet main/traveler in tight and go really deep. This reduces the mainsail's "profile" to the wind, thereby reducing power/heeling force.

I think many here on the forum have experiences with the "death reach" zone, where you really don't know what option (heading up or down) will cause the least amount of collateral damage.

The consensus is deep reach = drive down / tight reach = head up when overpowered. Between those two is the problem...

And I think all agree with your spin luff being too lose, with the boards being a bit too deep. From your dramatic steering when hit with the puffs, you were likely heading up too high to hunt them, and didn't have the boatspeed/apparent wind to turn that heeling into forward propulsion.