Re: fuel separator before or after primer bulb?
My setup is tank, bulb, fuel filter/separator. I see no issue with the sequence of the bulb and filter as long as they both are located prior to the motor.
Probably best to design the layout to suit the boats needs: With my tank in front, it was better to have the fuel bulb in reach of the helm for priming/starting. The water/fuel filter is in the aft where the 3 way switch is for attaching additional portable fuel tanks and easy access for maint/water draining.
I guess it is possable for some really neglected tanks to develope some crud that is is big enought to clog the ball valves in the bulb, but that would be the extreme.