- Work is near Embarcadero station (or possibly at home). I have a car but would consider selling it.
No need. Many neighborhoods have limited parking for non-residents. You get a bumper sticker for your neighborhood. Still need to move the car for street cleaning - and very close in, possible to avoid being towed away during rush hour.

- Where are the weekly crit practice rides?
There was a twice weekly series that used the Polo Fields in Golden Gate Park as a base. Not certain when they'll start up again.

- What are the climbing options besides Mt. Tam and Mt Diablo? Easily accessible without a car?
This one's easy. Google "49 Mile Drive". All the climbing you'll ever want.

- Marin or City or East Bay; taking votes. All 3 align with my personality in some manner; I'm still determining which would be best long term.
Only you can make that choice. Our politics and politicians are what they are, but this is also one of the world's great cities. Berkeley is dominated by the university. I've always like the semi-urban feel of Mill Valley, which is just a few miles north of the Golden Gate Bridge.

It's difficult to get value for dollar in the Bay Area. You may have to accept less space or even look for a roommate(s). Craigslist usually has short term rentals/roommates listings for the area.