I doubt he'll be able to quality for a loan (VA) with just his income. 

If I got a home equity loan for Property 1 and used the proceeds as downpayment for Property 2 and then got a 2nd loan for the remaining 75% purchase price for Property 2, when I sell Property 2, can I use the Property 1 loan as part of the cost basis for computing Property 2 capital gains?

By 2030, we want to have grown a portfolio of over 100 units, created a property management company that manages an additional 100-200 units, and, finally (and most importantly), we will have established a non-profit that is focused on quality, affordable housing that specializes in providing housing and resources at/on the "services cliff" alongside financial counseling and first-time home buyer education in our target area.Our target area is the Springfield, MA and Hartford, CT areas with dreams to expand to Central Massachusetts (Worcester, MA), Southern New Hampshire (Nashua, NH), and Southern Connecticut (New Haven, CT).Would love to meet up with likeminded individuals in our area!

At the current scenario, without knowing anything about you or your properties I will recommend either to look at a loan from your assets using DSCR loan.

For active investments I advocate considering how you can diversify WITHOUT ceding your competitive advantage nor the superior profitability of the niche your in.As an example my business is running an investment fund and syndication high interest commercial mortgage loans secured by income producing real estate. 

The two existing LTR units (on my family’s property) were built 5–8 years ago at a cost of about $80,000 per unit, so I’m estimating a 20% increase in costs for the new builds.My plan is to use the equity in the land as the down payment for the construction loan, which I expect will make closing costs the primary upfront expense.

The current lender refuses to do a loan assumption. 

Other than paying for an appraisal or BPO (and maybe a credit report), you should not pay a lender anything until your loan funds.

Initially, the business was cash-flow positive for the first three months, but things have declined since then.I received several negative reviews due to cleaning issues, and it took me over a year—cycling through multiple cleaners and settling for an average one—before finally hiring a great cleaner.

This term replaced "subprime" and looks a lot different than subprime loans of the past.