I'm at the nervous and cautious stage, but am trying to educate myself as much as I can before diving in.

My challenge is that I have a growing family (wife and 3 kids under 5), and it might be hard to move into a smaller space...any advice on potential options to get into the RE game once past the roommates stage for house hacking?

If you wanted pay a bit more for the property and have the seller pay back the excess to be used as your down payment, the bank needs to see those funds in your account for a month or 2 first or they need to come from a relative.  

My challenge is that I have a growing family (wife and 3 kids under 5), and it might be hard to move into a smaller space...any advice on potential options to get into the RE game once past the roommates stage for house hacking?

Even if you don't need it for this project this may help you in the future.At this stage in the process for you I feel like most questions will be answered just by asking for the refinance but you can also ask if their is a "seasoning period".Are you refinancing in an LLC or your personal name?  

It would not really affect your DTI though because you would be financing out of the PLOC in the refi stage (if all goes according to plan) so that loan would no longer be a part of the calculation. 

are some of the main things I'd suggest doing at this stage.

The Cistern would probably have an overflow drain to release excess water, hiding the leak.It's obvious the leak is past the main shut off.

In one land development and multifamily construction and leasing project, early investors were promised 10% PR raising money to purchase land and get to pre-construction stage.

I had planned to use hard money to fund my first BRRRR but after speaking with a hard money lender I am reconsidering this approach due to what seems like excessive costs.