I have an issue with point #2, filling up when you reach 1/2 tank - I think the gas mileage penalty due to the extra weight of the additional fuel that you're carrying around would easily outweigh the loss of gas due to evaporation during filling. That weight isn't much on most cars but 1/2 of my tank is 10-11 gallons, which is over 60 pounds of extra weight to carry.

On the other hand, I do agree that you shouldn't let your tank go below 1/4 - the fuel pump is cooled by it's immersion in fuel and running the tank almost empty could potentially shorten the life of your fuel pump due to the increased operating temperature.