1. Is okay, though it really only defers the problem for a few months, but that does allow for more attrition 🙂 are there criteria beyond time-in-grade? Does someone headed for Lt.Cdr. Have to go through the grade?
2. I would avoid this if possible. The feel at present is good.
3. I don’t exactly understand the proposal, but yes, seniority needs to decay with absence. Skills do atrophy with disuse.