I've lived through rehabs, flips, short sales and made lots of money on buying and selling real estate.

That being said, here’s what I would recommend for a thorough DD process:-Build a plan in advance (setup a spreadsheet, meet with the team, etc)-be prepared to take a lot of pictures -document notes with each room (we use notes on Apple and share it with the team)-align the team on standardizing information (example: what does “bad” mean, what does “okay” mean, etc - everyone looks at things differently and you want to make sure the notes are accurate during your debrief)-bring in professionals for things you can see, like sewer lines hope this short list helps! 

I think I’m more focused on long term gain, some short term cash flow is nice but I’m not planning to try and live on it or anything.

12 units, but 2 of them are short term rentals.

Before you take any action be sure to think carefully about what your goals are in the short, medium and long term.

The Short- Term Rental Loophole Explained (biggerpockets.com)

Helocs are great for short term debt!

The short answer is yes, they should provide you with an itemized reciept and if they are markign up, that should be a clear line item.

Please make your responses as short or as long as you want and I will read over them.

From purely a lending perspective, the projections from AirDNA and Rabbu are the only commonly accepted sources for underwriting a short term rental purchase or refinance DSCR loan.