I have reds in 2 ponds, one has grass and river bulrush, the other has 3/4" gravel basin. FHM, BNM and reds all survive together.
I see the Reds spawning up on the gravel pretty often once water hits 70. I haven't been able to actually observe them in earthen shores/bulrush/grass as far as spawning goes.
The only time I see them in schools is when they are new fry or a super calm evening they will be in groups near the surface.