What do banks usually require as a down payment?

I have tried a local bank here but my DTI and CBR scores didn't match their requirements and the loan officer wasn't very interested in even working on anything commercial.  

Hello I just finished the audiobook of "The Book on Rental Property Investing: How to Create Wealth and Passive Income Through Smart Buy & Hold Real Estate Investing".I just want to know if there are any PDF's on the " checklist what to see before buying a house" and a PDF for other 2 things like - "How to make an offer and what to check before completing the offer" - "how to find my Karma points for my loan so I make it easy on my bank"Edit : Also the guide on how to do Screening on my Tenants if possible(the one that analyzes the audiobook)

Do local banks generally provide mortgage servicing for seller financing?

Appraisals for bank financing are generally conservative to protect the bank.

@William Henze I'm curious to hear other responses from more experienced folks, but I did something similar and bought a duplex in Tennessee from a bank that was occupied. 

The larger banks are typically the worst.

I had one that with paying off the bank and the lien the seller was in the negative as in they had to pay cash up front to get out completely.  

My question is, which banks or mortgage companies do loans for under $100K?

I feel this would take a long time and have many strings attached with a traditional bank?