Now I am no expert, but I just went through the same with my auranti, and what I did is I had my tank at 25c when I introduced the fish to the tank, and after adding the fish I turned it down to 24c, and then I kept it like that for 2 weeks to a month, and then turned it down to 23c and so on. It took a while but the tank is setting at 21c now, and the fish didn't seem to notice.
But if anybody else has a better method than me please let me know.
As for flow again no expert but they would properly prefer lower flow, so they can cruise around easily, that seems to be the case with my auranti. But I do have enough flow so there's not really any despots in the tank.
On a side note what kind of substrate do you use? If you use sand or something along those lines, make sure the stone and wood is pretty stable, most snakeheads like to dig so you don't want anything sliding unto your fish. This was not something I knew when I got the auranti, so I had to re scape a little bit.