Any swivel bracket will have an umbrella mounting hole and screw lock. Also, I have found that unless you're using these lights at full power, you don't need a Y cord. The recycle time with the single plug is nearly instantaneous. I use the Cheetah 50cm square soft box quite a bit and their reflective umbrellas with the silk front. I also use their 24" small round soft box quite a bit. I think they call it a collapsible beauty dish.
Pick up a set of grids to help control light spill too. These snap into the standard reflector. I also use spring clamps to mount the batteries to my light stands. This keeps them secure.
My four Cheetah lights live in a Pelican case and I've never used bulb protectors. Haven't broken a single one in two years.