Re: water in fuel
I'd say it's almost certainly the sensor.... you can't get enough water in that short a time to trip the light. Have you drained the HFCM into a clear container so you can check to see if it really is water? I'd bet it's all fuel.
Aside from getting a really bad tankful of fuel, you don't need to replace the fuel filters any more often than 15,000 miles.... and a lot of guys go 20,000 between changes. Changing filters every 60 days is a totally unneccessary expense. Also, I'll post again after I dig up the part number.... get your fuel filters from your friendly local Navistar (Internaional) truck dealer..... LOTS cheaper than getting screwed by the Ford dealer.
Another tip.... now that the pumps are almost all ULSD, you need to add an injector lubrication additive to your fuel; I'd recommend Opti-Lube XPD, but a lot of guys add Power Service... white bottle in the winter, grey bottle in the summer.