Looks great
I wouldn't worry too much about rushing the lighting. FWIW, mine are under 175W (but a shallow tank - 12"). I doubt 250 vs 400 will make any difference off the bat, ie., either are fine.
As for flow - yeah, I think for now, just let him settle in. With time, try experimenting with placements and wavemaker settings (if you have one). I was somehow able to get my 75g to have a "wash" of water come from one direction, for a few seconds, then a pause, then a "wash" in the other direction. I think for me the trick was having two powerheads side-by-side on the same wavemaker channel - both aimed close to the surface - the outputs just agitated the surface, but the real "wash" effect came from the suction of the powerheads. Hard to explain but it's like water is "falling" towards the powerhead, giving as close to laminar style flow as you can likely get with stock powerheads. Other options are try for a gyre effect (whirlpool), or prop type upgrades for the powerheads, or Koralias, or Seios, or Tunzes .. or Vortechs.. etc. etc. - likely there are many ways that will work out.