Wow, that's a big tank. Lighting it is going to take some serious consideration no matter how you decide to do it. The 5' width makes it a little more challenging, but it depends on how you plan to aquascape.
If you can live with about a 3' spread the full sized Lumenarcs or Lumenbrites are still a solid reflector. You can keep them a little higher than usual since you have a shallow tank which will help with the spread even more. 4x 250w should do the trick. If you need coverage all the way out to the edges of the tank you could supplement with some T5's or LED's. I don't think an all T5 or LED setup would be practical for a tank of that size.
As for skimmers, I would look for something that utilizes efficient pumps such as the Sicce or Tunze pumps, or something along those lines. There's no reason you should have to use 200 watts to skim your tank.