If the property were owner-occupied, would I only receive credit for one rental unit's income, while the non-conforming basement income wouldn't count?

I’ve read quite a few posts about foreign investor financing but most seem to deal with non-citizen investors without US credit or personal tax filings.

What they said.....everyone over the age of 18 has to have a background/credit/ ID verification and sign the lease.

Another option could be a home equity line of credit (HELOC) if you have enough equity in your primary or second home.

However, aside from that, I couldn’t find much information about them, and the only online presence seems to be the wife’s LinkedIn profile (though I’ve never met her in person and am just going off her profile picture on Zillow).After submitting the application through Zillow, we attached our income (two months of pay stubs for each of us from our current jobs), work references, credit and criminal background, rental history, and the contact info for our current landlord (who just so happens to be my fiancé’s father).

All of those people also get credit/background checks. 

Either way if you personally guaranteed the note, yes it will affect your personal credit no matter who the property is titled to.

The Retainer Fee is credited towards whatever they buy from us in the 90 days, so in effect, costs them nothing.Note: we're not doing this to make money, but to avoid the time-wasters.

My first property was tough, (credit not in place was a challenge - luckily, got some help on this!) 

Given your financial constraints and the property's ineligibility for historic tax credits, this approach allows for reinvestment into assets more aligned with retirement account rules.For future real estate investments, you don't need an LLC for tax reasons.