Utilities, taxes (property, local vacation, & income), landscaping, furnishing / decorations / amenities, pest control, & supplies (soap, TP, etc) are the big ones on my STR calculator that you didn't mention.I'd also recommend using the enemy method to determine expected income.

Ask local property management companies what they are seeing for utilities for similar fourplexes.I don't know the age of this building but mine are 80s built.

Our locals will negotiate on sight distance but there has to be a reason.  

I recommend looking at B neighborhoods up in your local metro.

Partner with a local lender.

That 4-plex already has a local realtor.

I was just at a capital raising event in New York City pitching miami and columbus. by far there is more interest in miami for development, land entitlement, etc. you also aren't local so I'd discount what you say by like 80%. even if you are looking at "condo" investments, that's about the poorest way to invest in real estate so I'd say just you looking at that says something about your experience level. 

Do you have a floor & Decor location there locally ? 

I would send a letter and request a time to meet with them to discuss.I do have a question on your local market.

I'm not a lender but I know several good ones that are here local.