New rates are currently looking about 7%+I asked one lender about 2nd mortgages, with the hope of pulling just the equity out, but the rates seem to be 5 full points above the standard, so about 12% so that doesn’t let many deals work. 

The current rents for my area are around $1950-$2050, however my mortgage on the home is $2200. 

I obtained a signed pre-approval from a lender for a short-term rental (STR) investment at 80% LTV.

I am looking to build an ADU on the investment property and looking for a lender that will finance the ADU construction. 

It's a fine balance between economy and what you would do for oneself, but creating a space that feels like home should be of primary focus.If you're looking for some insight into re-leveraging any investment properties for capital improvements, furnishings, etc, some lenders can utilize AirDnA projections to qualify. 

Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

I have a mortgage on it which is up to date. 

Your financing should be based on your goals as well as your cashflow (after paying the mortgages, repairs, vacancies, etc.)

To add some color the home next door is worth about 20-30%% of ours but if we bought today the mortgage payment on it would be about the same as ours.

it's that simple.2. you switch to a landlord policy on or about the day the tenant moves in3. no, you don't refinance your mortgage just because a tenant moves in (unless i am missing something the two have nothing to do with each other)4. let the PM do this5-6 - up to you, you don't need either one when you're getting started7. too personal a decision to advise, but yes you need reserves - what if you need a new furnace or new appliances?