Yes, it is root bound. I’m thinking of just placing it in a five gallon bucket and add water and just see if the dirt holding the root ball will fall away.
Yup, that should work, although I would use a garden hose on very low pressure, and would remove any strangulated roots (where roots cross-over each other),
thin about 1/3 the roots or less, and re-pot in a slightly larger pot with fresh soil.