You can check them if you have a scope. Here's a pretty good article on it. Near the end of the article they mention the humps in the waveform. That's where you can tell if the pump is on the way out. http://www.motor.com/magazine/pdfs/032003_12.pdf
The pumps will work harder if the filter is restricted or if the tank is run low often unless it's the returnless system. The unused fuel is constantly run back to the tank on the non-returnless sytem and gets heated from the engine. When the tank is low, the fuel gets hotter and so does the pump causing heat stress on the pump. Thus wearing it out quicker.
I don't think it matters how much you drink, the system won't know.