Welcome to the forum!
I am amazed at how many of us had bees before Varroa entered the scene, and are now returning to beekeeping.
Beekeeping is a lot different from when we were young. I kept a single hive, took honey, and only worried about AFB and wax moths.
Now, it takes a complete education to stay on top of managing all of the threats to your hives. Which means more toys ... uh equipment ... to buy.
I don't have any advice on flow-hives.
Enjoy the wild buzzy ride with your bees!
-WM