Prepayment penalties- usually 1-5 year terms.

I don’t believe it is that simple.

Does anyone recommend books, courses, or anything to help me learn the general terms and what it takes to become a private lender/broker?

If you do fight to keep it, and go down (which you most certainly will), the term, "an unpitied sacrifice in a contemptible struggle" comes to mind.Sell it, use the money to set your net worth on an increasing trajectory, turn that inheritance into something positive.I'm sorry to be giving you this advice.

There is also potential to have a 4th bedroom with a simple layout change inside but I haven't decided that yet, as it would be on the smaller side.

Prepayment penalties- usually 1-5 year terms.

If you have private money available, you should explore those as preferable options due to terms and upfront coasts as compared to HML options. 

Call your insurance agent and hold them accountable to what the policy actual says (terms, conditions etc).  

However, my focus is on long-term rentals, creative real estate (like buying sub2 and with owner finance) and buying mortgage notes.  

Also love @Patrick Allen's reply mentioning.(1) HELOCs on primaries are easier to obtain(2) High rates may make cash flow difficult unless there is a clear & compelling refi strategyItems I'll add from my seat.(1) Although rare we(Lower.com) offer HELOCs on investment properties, but the terms will always be better on primaries.(2) If you're moving into the next home, needing to only put ~5% down doesn't leave you very exposed to the higher rates of a HELOC.