I have a similar situation in regards to your initial statement.

I’m confident my bf knows what to look for before buying an investment property, but I’m not really sure how to do the research on my own.

I am confident there is a clause included regarding drug activity..I'm not a lawyer, so don't rely on what I say as fact. 

Navy federal approved me initially , but denied me and said they couldn’t because it’s a duplex and second home , which limits my opportunities in a way.

I was confident and I did what needed to be done because I already knew no mere mortal will beat me.True or not.. that's completely irrelevant!

Collect and track information on leads obtained from drip campaigns and conversations in individual lead file.Route inbound calls and record calls in the lead’s file.Automatically populate lead database with information from website contact form / squeeze page and initiate drip campaign.

My plan was to rent both units out at a premium upon completion and then refinance the building to harvest my initial capital investment back.

My concern is if we buy a turnkey property and put 20-25% down, how would we be able to add value to the property in order to refi at a higher price so we may get our initial money out and use it to buy another one?

That is part of an initial meeting understanding their requirements.

A few things to note, I will be house hacking the duplex, the duplex isn't in my name, it's in my fiancee's name, and the card was initially opened as a sole proprietorship for some property management/repair work I've done.