Might be a good fit for you since you mentioned you have a baby and your age.  

Of course....just stipulate that you are allowed to use it!!!

which is kind of impossible in this hot market from MLS This one fits well in my portfolio.

Historically, I have invested mostly in the stock market, but I've really spent some time learning more about RE investing, specificallly on the SFH and small MF side, and I'm thinking this would be a good place to deploy some of my capital (if done correctly of course!). 

Of course, you can just pay cash for construction expenses, but this will need more initial investment and you'll have lower return on your cash. 

Of course everything depends on the situation of the seller, so I don't think there is a specific formula or ratio for that.

Of course keep in mind, pre approval doesn't mean you have to use that lender.

Edit: Shoot, can't believe I didn't think to add this as it fits my interests, but I think the Smart Home/Automation trend is really cool and hope to be able to get more involved with that.

Of course, this is assuming you have your personal financial house in order, i.e. no large credit card debt or large personal loans.

This plan is a great fit for many independent contractors.