The reason your fuel mileage is abysmal is because you have V8 with 3.92's at 80 MPH. The gears are going to have you running much higher rpm's than a truck with something like 3.21's or 3.55's, and a 5.7L is going to burn a lot more fuel than a 3.5L running the same rpms. Those gears and a turbo V6 are great for efficiency, but they suck for low end torque. Unfortunately there's no magic combo that works fore every condition. You just gotta pick the one that's best for you and accept the short comings along with the perks.
As for the fuel. 89 is "recommended" not required. They say to use 89 for "optimal" performance. It can, and will, run 87 just fine. I ran 89 briefly but I've been running 87 for the last couple fills and I haven't noticed any lack of performance. Although, like you I'm driving Ms. Daisy, so there's no spirited acceleration. When I plan on towing or hauling heavy loads I'll probably run 89, but I have no justification for the added $0.50 per gallon for regular driving.
This is because they design the suspension for comfort. That comes at a cost. It'll absorb rough roads easier, but that makes it sag much quicker than a firm spring. Much like gears/engine it's a pick your poison kind of thing. Either a smooth ride, or a work horse. FWIW, you can easily swap out the struts and springs for a firmer set to have a more F150 type ride (and load handling).
Yeah, the F150 does feel more "truck" like. A little more rough and rugged. Less refined, and more ready to work. Although if I'm looking for a work truck I'd probably get a 2500/F250 instead of a 1500/F150 anyway. The light duty truck is transportation, that can do some work. And there's no mistaking, these will do some work even if they sag a little in the process. A set of air bags for $100 makes a big difference too.
