Virtually every mortgage broker* will use the FM Selling Guide for determining eligibility, or you google "fannie mae underwriting guidelines" for high level details.

TOH, location, age/quality of the assets, etc...

I own some small multifamilies in Concord and High Point, NC.

(I also would like a loan that doesn’t require a high down payment). 

I look for low crime rates, good schools, high rent to value ratios sometimes as high as the 3% rule. 

I read that there is a high wild fire risk.

As a general rule of thumb, no one ever lends for less than the rate of a high yield savings account.  

Metal roofs are highly recommended and should last for a long time I'd want everything to be gone form the old roofing and everything inspected properly before the job gets started.

the cap rate for single family in san jose is maybe 1-2% ; DSCR is 0.25 ; but with very creative strategy we can make it into 0.8-1.1 but the key is using more tenants per unit, also home that has basement and ADU like me, the unit can be rented and while my dscr is above 1.0 but banks can't use it so we kinda stuck to leverage but this creativity of multiple tenants per single family.i am now trying 40 year IO program from one of the lenders such as yours to quality, also i will try no-ratio DSCR at some point.Seriously, by combining hefty cash position + flip program + rent out to multiple tenants ; and sell it few years later, this is the less riskiest project we can do as landlord/flipper.

Seems like the general consensus is the quality of the inputs and the ability to sensitize them is the most important aspect / biggest challenge, so that you understand the potential outcomes.