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

Here is a recommendation I have for you as you begin to figure out what area you want to invest in.This website is a great reference point for figuring out what each area is like. https://www.areavibes.com/It gives you a total LIVABILITY score for each street and zip code & discusses crime rate, schoolsUse this rating and classification system I have created over time to get an idea of the "Class" for the area - A class B class & so onHere is my rating & classification for each livability score.80 and above A+78/79 A76/77 A-74/75 B+72/73 B70/71 B-68/69 C+66/67 C64/65 C-60/63 D59 and below FBest of luck and let me know if I can help answer any questions! 

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

I also don't want to focus on one market, and not be able to score the right property for who knows how long, and then end up missing out on other locations, as being a long distance land lord is very popular as well.

Most HMLs, depending on your and your partner's credit score and experience, only require 15%-20% equity/down payment from borrowers.

Take stock of your current credit score and accounts.

His credit score is fine but his income is showing too low to get the loan, so I though maybe I could use my HELOC to make the purchase and do a Lease to Own.

@Helena Goyvaerts rate for a 30-year fix would be at least 8.5% with some points (1% of loan amount).Most DSR lenders have a minimum credit score requirement from the applicant.

-Max LTARV is typically 75% -Is a 12-24 Month Interest-only loan with a balloon payment - Minimum credit score is typically 600 -Interest on the Rehab is usually paid per the total drawn amount.