Do springs and bumps first. It eliminates wheel hop and the truck rides smoother, on and offroad. The improvement is worth the money and time spent.
As for shocks, it's well worth it if you are doing high speed offroading often. The difference is as big as going from a normal f150 to a raptor.
If you are doing lower speed offroading, or have choppy pavement, stay away from the icon coilovers, even as soft as they can go, they are still very stiff due to the digressive damping and high spring rate.
I'd say wait until the stock dampers let go, then upgrade, and have the stock shocks rebuilt for use as back ups.
The on road ride with the 3.0's is slightly rougher with the fox's, and a lot rougher with the icon's. For on road comfort, the stock coilovers are hard to beat. The stock rears seem to be a bit rougher than either 3.0 offering though.