Expat package - what needs to be in? (San Francisco)

Always signaling that I would be interested in a job overseas, my company’s HR just approached me with a possible job option in San Francisco. All I know for now is that it would be for 3 years and that the office is right in the financial district.

HR wants to get in touch with more information and discuss the package further later this month and I want to be prepared for the contract negotiation as I cannot afford overspending whilst working in SF. Therefore, my most urgent questions are:

1) What would you recommend to be the minimum yearly income necessary to afford a 1 bedroom flat in a safe area within a 45min max commute radius? My partner would move in later but can currently not quit his job.
2) Where would that safe area be? I don’t care if it is not “the place to be” or if it’s foggy, I just want to feel safe and it should not be completely run down. Do you have any preferences and maybe a real estate or relocation agent you can recommend?

Although we always loved the idea working abroad for a while, I am currently torn between being either ecstatic (working abroad and hey, it is San Francisco!) or disenchanted by the idea having to live way below the standard I am used to, simply because I cannot afford anything else.

Thank you very much in advance for your help
Riccarda