that is strange that it would have that much draw...
google the part number on the side of the pump, it might be something dumb like that particular pump is meant for a different car or something like that. Usually doesn't make a different, but who knows.

I'd go through and double check the grounds on it. the speed bump issue makes me thinks that the ground is the problem. Instead of grounding it through the harness. Make a new ground on the chassis right next to the pump. That way you know it is good.
double check the connections on the pump itself. don't want those to be the least bit loose.
while you're back there, get the car idling and see what the voltage draw is with a multi meter.
In my experience, it seems that those pumps can sit out brand new, on the shelf for months and months with no problems, but as soon as they get used, their shelf life drops to near nothing. so the pump could be bad if it has sat out for a while.

as for the inline pressure gauge, I'd say to do it right between the filter and the rail. I've always been told you want it as close to the rail as possible, if having a gauge on the FPR isn't an option. And you want it after the filter.
Just get a nice little water filled one that can handle the vibrations and stick it in there.

EDIT another place to double check is where the wires go through that plate. Every so often, they pull loose, wear away, or whatever and causes it to short out that way. both on the plate that goes on the tank, and the cover.