However, I've researched different ways of doing this, such as a home equity loan, Home Equity line of credit, and cash-out refinance.

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).

CA taxes residents on worldwide income but may provide a credit for taxes paid to other states.

If you play your cards right, you can have the permit submission package ready for submission the week after Closing.

Check with a few local credit unions as they usually have the best HELOC offerings.

my research shows 2.99% fee with Debit or Credit card to tenant if they pay use these forms of payment.