I understand (by you saying it's an algorithm) that its more complicated than a simple "max 20% income" or something. 

They could be shorter, but often are longer, depending on the complications of the transaction such as; How many liens are on title, how cooperate are the seller/borrower(s), and what does the banks value come back at, etc.

if too complicated, i will hire an agent, but hope to save some money (one-month rent) because I already bled a lot by doing rehab...

On top of the usual challenges of working on a historic project such as this, the previous owners of the building had done a large amount of unpermitted work over the years, complicating things further. 

There are complicated, expensive, legal ways around it, but talk to your lender first.

MA has a non-judicial foreclosure process.

I'm not a lender, but having the LLC will complicate things with getting a mortgage. 

It will go to accredited investors but there is some friends and family that I have in mind to show this too which is why I am trying to make it easy to read and not trying to over complicate it and provide some basic info.

Being lake front probably complicates things due to proximity to water (drainage, environment critical area, etc. 

If you want to scale then spreading your cash, HELOCs, etc with lenders allows you to get into more properties at a time.Regarding the example, terms can be different, or some lenders won't lend if there's no rehab component so you can see how it might get a little more complicated than it seems on the outside.