@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.

I'm not sure if they still have the 2 year requirement on income if it's going to be your primary residence.

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

No personal income or tax returns are required.

You'll want to read Maryland new requirements for landlords.https://dhcd.maryland.gov/TurningTheKey/Documents/HB693-Land...

Lenders will lend the lower of the amount between LTC and LTV.Do you require an appraisal and survey?

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

I'd ask for vet documentation for proof pet has received all state required vaccines.

(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.