Upgrading motors

Hey all,

I currently own a Felix 1.5 Rev E, and I'm looking to upgrade the electronics from a RAMPS board to a RUMBA board, and upgrade the motors in the process, but I'm having some serious dificulty in chosing the motors.

Firstly, this is the board I'm planning on getting: [www.reprapdiscount.com]

Secondly, the plan is to use the following motors:
X axis: NEMA 15
Y axis: NEMA 15
Z axis: NEMA 17 (Linear motion on with the threaded rod)
Extruder 1: NEMA 11
Extruder 2: NEMA 11

The extruder is going to be a direct-drive E3Dv5 based design, something like this [www.3ders.org]

Now, the plan is to get all the motors EXCEPT the Z-Axis NEMA 17 from Zapp automation. The problem is that it's a minefield as far as picking the right one. How do I know what to go for as far as things like voltage rating, current rating etc? All the motors are pretty much the same price, but I don't know how to figure out which ones I should be ordering? I know that I'll have to probably rewrite a load of the electronics code too, but that'll come later. I have to figure out the motors first!

Help please!! :(