Since I haven't fully decided where to invest, I don't want to have to fill out multiple applications and credit checks.We can refer you to a few lenders that other OOS investors have worked with in the Central Ohio/Columbus region check your pms 

By multi-family, I'm referring more to duplexes, triplexes and fourplexes, as opposed to larger apartment-style propertiesMy understanding is that 8-12% cash on cash is considered standard or good, but is this more for SF or MF, or does it include both?

When I see that, I usually take it as good but still consider other factors more heavily like length of employment, length/quality of Landlord reference, etc.

This strategy is often referred to as BRRRR on Bigger Pockets. 

FHA defines it as "A Principal Residence refers to a dwelling where the Borrower maintains or will maintain their permanent place of abode, and which the Borrower typically occupies or will occupy for the majority of the calendar year."

Note that 'value' refers to the original value, not current value.Hypothetically, presuming you & the loan meet HPA requirements and if your lender failed to remove PMI, submit a complaint to the CFPB and let them fight for you.

2) When you find a wholsesaler you would like to deal with, or even an agent who likes to deal in that sort of thing, is it appropriate to ask for references? 

She said she was thinking about referring us to another agent that works closer to where we have been looking lately.

I have come to know www.citybldr.com as a reference, and they are similar to some extent.

When someone sells a property, they are usually buying something else so you get a second transaction or can at least refer them to someone else for a fee.