Repositioning a 12-unit with 50-year legacy tenants - Bay area CA

Evaluating a 12-unit in the Bay Area, built ~1956. Strong bones, dated finishes, full gut renovation planned.

The complication: several legacy tenants, one in place 50 years at roughly 25% of market rent. City has no local rent control, but the property falls under AB 1482 — so 5% + CPI caps and, more importantly, just cause eviction protections.

Looking for input from operators who've actually repositioned an occupied Bay Area building:

1. Tenant buyouts — what's a realistic number for a 50-year tenant paying a quarter of market? I've seen $20K–$100K+ referenced. What actually closes, and how do you open that conversation without souring the whole building?
2. Substantial remodel under SB 567 — has anyone used this post-2024? What scope of work has held up, and what did the permit and notice process look like in practice?
3. Ellis Act — for a 12-unit this means withdrawing all units with multi-year re-rental restrictions. Has anyone found this pencils, or is it effectively off the table at this size?
4. Underwriting — I'm modeling on in-place income with no assumed turnover, treating any unit that vacates as upside rather than plan. Is that the right posture, or too conservative for this market?
5. Due diligence — beyond estoppel certificates, what have you found that a rent roll missed? Unwritten concessions, verbal agreements, undisclosed occupants, protected-status tenants?
6. Renovating around occupied units — is a phased approach as tenants naturally turn over a viable path, or does the disruption create more problems than it solves?

Not looking to displace anyone unlawfully — trying to understand which paths are real and which are folklore before I commit.