@Edgar Duarte Selling now under the primary residence exclusion avoids capital gains taxes, allowing you to reinvest the $500K equity in diversified assets like index funds or additional rental properties.

If borrowing, use a non-recourse loan since personal guarantees aren't allowed.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Second, Texas also allows Texas homeowners to do cash-out refinance their primary residence.

But the IRS allows this deduction to both of us, due to them taking shortcuts in their auditing process.

Majority of DSCR Lenders do not allow Manufactured homes but do allow for Modular. 

The lender clearly didn't communicate with you or set proper expectations, which is why it seems the expectations you have are inaccurate.Most lenders will NOT allow you to order your own appraisal/BPO. 

The Purchase and Sale Agreement is the contract that you and the seller sign which allows you the option to purchase the property at the agreed upon price.

Unfortunately - my current lot for my primary is 1 acre and VERY sloped, and close to a water source (creek), so the county has not even allowed me to permit my downstairs finished basement without an extremely costly renovation to our septic (over $60,000, and that doesn't count demo'ing and replacing our driveway to get to the existing tank and leachfield), and even if I could permit it, it would essentially need to be a treehouse in the redwoods due to the slope (not a bad idea though, I would actually love a livable treehouse on this lot!

I would allow for differences of opinions that are amicable, and even sometimes heated, as long as names and profanities aren't used.