I have a question about the crunch lab.

The solid bar that it has. What is it for exactly? Does it add anything special to the sound? And whats the difference between putting this bar facing the neck or the bridge?

Dimarzio explains on their website under the Dsonic, which is the model that the Crunch Lab is based modeled after.

With the solid bar towards the bridge it's supposed to be brighter and good for drop tunings.

With the Solid bar towards the neck, it's supposed to have more bass, be a bit louder and a touch warmer.
It's called a "rail." It's just a different kind of magnet than the usual slugs you see in most pickups. Usually, a rail gives a bit more of a hi-fi sound, and doesn't lose as much volume as a regular pickup when you bend strings, since the rail doesn't have the narrow field that slugs do.

There can be a slight character change in flipping any pickup north/south due to the different amounts of winds on the coil. The magnet probably makes a difference, too. Usually a pickup just sounds a little brighter or bassier depending on the orientation - it's not an enormous difference. More of an issue is that flipping only one pickup puts it out of phase with the other when two pickups are selected.
OK thanks.

It's no problem if my guitar has a 5-way switch right?
And is there anyway I could be sure that the technician has done all the wiring right??