Basically the plan is to be constantly causing damage while putting yourself out of harm's way. For gear, faster walk is essential, but otherwise more tilted towards attack than defence. Probably use a 2h crossbow for heavy hitting (a bow makes sense if you throw in Archery somewhere, though). Not sure about Discipline costs with 3 1/2 purple skills, so I put in Perfectionist and Carved Stakes to be on the safe side. There's a good case for Numbing Traps, though.
I suppose your themed build could work. Evasive Fire as hatred generator will drive you nuts thought, Vault should be enought. I would propably change it to Entangling Shot or one of stunning generators.
Another thing that might improve your build would changing strafe rune to let you move at normal movement speed.
Seems like a good idea but you're not going put out enough damage with strafe and evasive fire to take down enemies at an efficient pace. Spike traps do some damage but I don't think tits going to be enough to take down large groups, or elite enemies. I would get rid of smoke screen or caltrops and add another skill that can output some damage.
@Kebel: I think I'd rather put an offensive rune in Strafe, as the damage is a bit puny otherwise. If you really need to run away there is Vault (maybe Action Shot is better than Trail of Cinders here, will have to test how the damage works in practice). Also, this build maxes out Tactical Advantage and makes liberal use of Caltrops, so a lot of the time she's going to be on a speed boost versus slowed monsters, at which point a speed rune seems like overkill.
Evasive Fire takes some skill to use, I think. You don't want the backflip to trigger too often, certainly. (I hope Blizzard fixes the 'backflip against the wall' thing, as it makes no sense for the supremely tactical Demon Hunter to be so unaware of her surroundings.) If you just ignore the backflip part of the skill though, Covering Fire deals respectable damage by the standards of Hatred generators. Entangling Shot is a good idea, though, and it fits the theme. Maybe Chain Gang could work (assuming all four targets take 75% damage) - the rest don't look like they deal enough damage.
@GanjaHunter: I don't think elites are such an issue, but big groups could be a problem. On a purely practical note, if I wasn't going for a theme I would probably throw in Volatile Explosives as cheap AoE, or Cluster Arrow as a big Hatred bomb (the weakness of Spike Trap is that you can't really spam it). The build is never going to be the fastest killer when things are going well, it's more that you can always keep firing when facing more dangerous monsters. That reliability in turn means you can wear very damage-oriented gear, because you almost never have to tank anything. (Obviously you need some protection, but far less than the DH who dukes it out with Rapid Fire, for instance).
Thinking about the passives, Steady Aim is probably better than Cull the Weak for a build that is so good at evading monsters - '10 yards' isn't as far as it sounds. If Discipline turns out to be manageable, some kind of damage boost could appear in place of Perfectionist as well (probably Cull the Weak or Archery). I want to keep Tactical Advantage, because if this kind of build can't make good use of it, then nothing can.