My understanding is that if the people investing (which doesn’t matter if it’s 3 people or 100 -I don’t think) don’t have an active role or responsibility outside of the money, then the deal should be structured as a security.  

It depends a lot on price point, location, and the “showable” condition other active/pending/sold listings within the neighborhood. 

Your best bet is to bring the bank into the conversation and make sure they're okay with what you're working on with the owner.

What is the bet way to hire public adjustor?

For subject-to transactions, the POA won't get around the "due on sale" clause, but it will help you do very important things like cash escrow refund checks and insurance claim checks, and other borrower-centric activities.

They have been life changing for us and I am sure for most of the active members on this site.

So as a 'safer' bet, we decided that using FHA loans with a 30 year-fixed would be our best option since we intend to buy and hold.

I bet many might not..

If they are floating, the may go up each year which will impact your cash flow.Your best bet is to secure a loan with a term length that is longer than your projected hold period.

It's 99% likely that those 12 offers were submitted by clients that have an active buyer's agent.