Ford - Ranger :: Truck Suddenly Died On Road - Check Gauge Light Came On

Ford Ranger 20012.5LManual Transmission4 Cylinder Engine4x2 Drivetrain~160K Miles

While driving home tonight, my truck suddenly lost power, as if I turned the key to turn off the motor. There was a beep, the one that goes off whenever I open the door while the key is in or the light is on, then the "Check Gauge" light came on (the one that warns me when my gas tank is near empty), following that the yellow Battery light came on and finally the orange "Check Engine" light came on.

I pulled out into an empty dirt lot, but that was pretty difficult as the power steering was gone (since the truck was off). After parking the truck, I turned the key to the actual "Off" position, pulled the key out and gave the truck a few moments. I put the key back in and tried to get my truck running again. Of course, it didn't work, but I figured it wasn't the battery because it lacked the sputtering motor turn. There's that and the battery is under two years old. The truck seemed like it really wanted to turn and start, but it lacked a certain something to get it up and over that last hill to vehicular movement. I don't think I was lacking gas, since it should have given me the red "Check Gauge" light and even if I was, I know I have another 5 miles before I have to fuel up (I would know since I've tested it to see how far it would go on that light). I was pretty low on gas when this happened, so the thought came to me that maybe my gauge was starting to get a bit wonky. Then a more realistic thought came to mind.

I've had this bad habit for a while, where I fill my gas tank to only about a quarter or a half at the most. Part of it stems from a paranoia of having somebody siphon gas out of my truck at night; yes, I could have fixed this by installing a lock on the gas cap (albeit, my counter-argument is that it's better to have them take the little bit of gas than have hundreds of dollars of body damage from an aggressive thief). Anyway, I've heard that this habit of filling the tank below half can speed up fuel pump failures. Despite this, I've had no other symptoms of a fuel pump failure coming, as I haven't experienced any issues with surging/bucking.

So here are my questions:

1) Am I right in assuming it's a fuel pump failure?
2) Are these instructions to fuel pump replacement accurate? (Yes, I know the DIY Matrix provides every reason on why I should avoid doing this myself, but my wallet I'm itching for a project.
3) If it's not a fuel pump failure, what could it be?