First purchase advice - 3 properties available

[Tyler Walz]

I recently discovered BP and am in a market with no inventory so I decided to look at a particular run down block I am familiar with in my city that has various multi family properties on it. I realized 3 of them were owned by the same person on the same street, and after some Google detective work I found his cell and learned he was 62. I decided to call him and he answered so I asked if he would ever be interested in selling...and he said "actually yes, I am ready to be done" (beginners luck for me, I guess). The 3 properties are a duplex (4br 2ba each side), and 2 quads (2br 1ba each unit). They have great BRRR potential, and are all occupied currently. I own zero properties at the moment other than my house, but I am ready to dive in. I am looking for advice: do I start with the duplex (which I feel has the most potential) and tell him I want the others as soon as I am done with that one? Do I make a play for all 3 right off the bat? How do I structure the deal? I do have an investor that would front me the cash and I'd pay back after the refi, but we have only talked on smaller deals recently ($150-200K). This would likely land somewhere between $550-750K if I went for all 3. I have no official real estate experience and am not sure how to really proceed from here. The current owner said to make him an offer. He had all 3 listed on the MLS in 2017 for a total of $580,000 and took them down months later. Like everywhere else, our market has appreciated quite a bit since then. We're in the top school district in the area and a highly sought after town.

Any advice of how to approach this would be much appreciated.