@Sung Yu You can 1031 exchange your fourplex into a single-family home, provided it’s initially used as an investment property (rented for 1–2 years) to meet IRS requirements.

A DSCR loan is going to require more down, have high fees at closing, a higher interest rate, a pre-payment penalty, and will require you to have cash reserves that you likely don't have at the moment.

What is the typical minimum investment requirement?

It is required by the law and the Code of Ethics.2) There is no such thing as not going through your brokerage when you have a license.

No personal income or tax returns are required.

If so what are his loan requirements?

A smart seller/listing agent will likely require a large EMD to tie you to performing on your offer, so be prepared for that. 

(eg, if your lot is not the standard 25 x 125, but some other multiple where the width is actually skinnier than 25, and the lenghth is longer than 125, and you want to reduce side setback requirements, eg.) 

As for non-bank loans, I'm familiar with a loan program that provides 100% financing, but it requires a minimum 650 credit score and proof of funds covering 12 months of interest.

Yes, I share the same feelings and dont understand why the information and steps required is SO extensive!