May in the rockies can be sunny, rainy, or snowy. Please check weather the week of travel and plan accordingly. West Yellowstone is high elevation.
Yes. When hiking we recommend carrying pepper spray - which is to be sprayed at charging bears for deterrent, not to be applied as repellant.
No. They are 200 degree thermals. There is a pool in the hotel and you may jump in the lake.
No. Doing so over-does the bird and there are things like arsenic in those geysers.
Bison can run 35mph and in an initial sprint a griz can cover 50 yards in three seconds. And if you see a baby bison looking cold, please assume mom is close rather than loading it into your rental car.