After two years, you can qualify for a loan or continue working the seller-finance angle. 

I don’t know if I should invest in the Jersey market and put maybe 20-50% down on something, make less cash flow and make more appreciation, or every two years or so maybe buy something fully cash (my own $) in the Midwest let’s say 5-10 units and make more cash flow with no debt as with the income I make I can just save and buy more, don’t necessarily need to leverage in some markets.

You can also find real estate investing groups through meetup.com, Facebook, or a Google search.

The right market for you depends on whether you prioritize cash flow (Augusta, Columbia) or long-term appreciation (Greenville, Huntsville).

Any contractor recommendations or lender suggestions for short-term financing?

You should consult an attorney or CPA for your specific situation.An LLC is useful for two things: anonymity and legal protection.

Turnkey deals or more do it yourself type BRRRs?

Very similar to properties in Oregon we've sold and for sale.

Although you might be able to get away with it for a while, all it would take is for a neighbor to call in and you could get shut down or fined.

Umbrella insurance is usually a very large policy of $1 million or more, extending your coverage for larger situations.