I've also had the helo dunker training; at the facility where I did my latest certification it's been replaced with an Osprey mock-up. Never got to see the new dunker in action, but I had the impression it could be fairly violent, whereas the helo had a relatively gentle water entry and roll.

As for the masks, I picked up a full face respirator from Home Depot that can take either particulate or hazardous fumes. The respirator can be used with