CA taxes residents on worldwide income but may provide a credit for taxes paid to other states.

Consult with a tax professional or accountant for precise guidance on your specific situation, as tax rules can be complex and may vary depending on your individual circumstances.

Depending on whether you have US FICO, US bank, Visa, etc, the programs you can qualify will change.

Yes you can get a HELOC on your primary residence even if its 2-4 units it depends on the bank.Try a local credit union because some banks or CU's will only do them 1-2 units, but there are ones that open HELOC's for 3-4 units too like BECU.org.

Lenders have a minimum loan amount for investment property financing depending on the lender and whether conventional or DSCR. 

This company has one person depending on situation (marketing, maintenance, leasing etc).

Depending on their responses you'll want to speak with a civil engineer to get their cost for helping you through the process.

What if no other insurer will provide a new policy, but my lender requires full ongoing coverage, and would treat a naked situation as a default, meaning immediate loan repayment or foreclosure?  

'Need to find the first deal' - they are everywhere, are you wanting someone who has done all the work and effort to provide this first deal to/for you? 

It depends on what the partnership agreement says --- especially on the question of how much control each partner has.