Yes many easy commuting options to NYC such as the lightrail, path train, ferry and bust.

Another option would be working with private lenders to see if they're open to your idea should you need additional funding. 

There is risk in both options & as an investor you need to weigh those risks & stand firm on whatever you decide. 

I havent gotten an insurance for this and a week after close I consulted some insurance provider and he didnt offer me insurance options.

You should have some options! 

Off-market property is the best option for fix and flip, but since you are planning to live and flip, some on-market properties would also work.

Staging your house well can help you attract more attention from buyers, which ultimately helps it sell faster and maybe for a higher price than an unstaged home (see visual):What Are My Staging Options?

Several options you can explore to get the down payment capital: Solo401k; HELOC on personal residence or from equity of the SFR; Cash Value Life Insurance Policy; Business Credit; Private Lenders, to name a few.

I suggest your next lease have such a clause and that you make sure you can find the lease (but i have also somehow lost a lease recently).For where you are now, without a signed copy of lease i believe your options are limited.  

If you use the Heloc option and decide to rent it out, don't forget that property (or you) will have to cover both your primary and secondary position notes.I don't personally see Marin being a great mid term market.