In need of flathead advice

[Struck24]

So I've decided to try and get on some of these monster flatheads you guys are catching. But I do have some questions that I would really appreciate any insight on. I drove a good portion of old mine road today and found some potential spots. Or atleast I think. The one spot in mind is a flat of fairly slow moving water, about 60-80 yards down river of a rapid section. Water seems anywhere from 6-15ft deep. Mainly rock bottom. And some algae/weeds around. The only problem is I'm fishing right down from a small island, so my questions are:

Are these flatheads consistent as far as which direction they run when they take bait? (Upstream or down) my fear is they will run upstream and be on the other side of the island.

Is the popular bait used whole bluegills?

And are circle hooks the way to go?

Once again any advice or help is much appreciated, thank you in advance!