Before you get any further, if you haven’t, I would highly recommend writing out your specific investment goals, your reason for investing, how active you want to be, if you want invest close to home etc.

My parents are essentially giving me 3 homes to tackle myself.  

BTW, I have a great agent, an 800+ credit score, a high paying tech job, no debt besides my mortgage, a home that's difficult to get a HELOC on because appraisers can't figure out what it's worth (I live in the country in a very unique mid century home), but only a small amount of cash.

If you want an attorney to order one and then review, and explain it it would typically be about $150 in my area. 

Typically no financing for foreigners....so are you ready to pay cash?

I would do a HELOC, because if you don't want to take the money out you don't have to pay the interest, on a home equity Loan, the full amount is going to be advanced when the loan funds, and you will pay finance charges on the whole amount.We do investment loans on new construction, Typically we can do 60% of the land costs, and up to 100% of the vertical construction, not to exceed 85% of the Costs.Thanks,Dustin

I am currently interning this summer with a big home builder you may have heard of (PulteGroup) where i am working directly with construction managers.

I've found a small home builder that needs financing. 

I'm a first-time home buyer interested in house hacking. 

Here are some reasons ADU additions in single family zoned areas are typically a poor RE investment:1) The value added by the ADU addition is often significantly less than the cost of adding the ADU.