Does ST have a separate Cortex M4F series or are its M4 parts essentially M4Fs?
Yes all Cortex M4 from ST include a floating point unit and are thus essentially Cortex M4F.

Other manufacturers do this differently. Like pointed out in the comments there is Microchip with the SAM4C has a dual core implementation where one has a FPU and one has not.

So keep looking when you change to a different manufacturer.