Most of my clients run their SFRs at a 25%-30% (excluding vacancy/credit loss) operating expense margin and most of the banks I deal with on their DSCR loans underwrite using 35%.

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

I ran some quick numbers and would estimate (assuming you have good credit) you could borrow around $415k-$420k, which includes funding 100% of the rehab costs.Have you calculated your expected profit based on selling after rehab and if you decide to keep long term? 

Also remember just because a loan may qualify as being assumable the lender will go through a thorough underwriting process to confirm you meet eligibility for the loan.I have seen a guru teaching people with poor credit to go after these types of loans and it’s unfortunate as many would most likely not qualify.

If the students do not have the income or credit to warrant the rent amount, I would require that they get a cosigner (like a parent or another relative that can vouch for them).

This also includes a few credit cards that are used for business expenses.

This can be a city or neighborhood.We manage a lot of Class C properties in the City of Detroit, so previous evictions are common.We typically do NOT allow within the last 3 years and we want to see stable employment, income and no other major credit issues since.For Class B rental we're looking for no evictions in last 5 years.Class A, would be at least 7 years.Of course, there are exceptions to all of the above for extenuating circumstances the applicant is willing to provide acceptable documentation for.

sometimes to reduce borrowing costs, I'll use a hard money loan solely for the purchase, and then pay for the rehab in cash or use a 0% credit card (I don't recommend that for new investors!)

Next year i'll hit top pay and should start bringing in 1.2-1.3k a week. and the year after that i plan to move to linehaul and make about 2k a week.I do have a lot of debt, or at least it feels like it to me. the breakdown being;23k in college debt i got getting a bachelors that i never used across 5 loans ranging from 3 to 5% interest rate5k in bank loan debt i got getting my trucker cdl a at 12% interest rate.2.5k in credit card debt from not having an emergency fund and then having emergencies.

Depeding on the amount get a credit card that has no interest for 12-18 months.