The more i read the less i know!

So i resort to asking some advice from all please.

My idea is to end up with something that i can do wood cutting and some aluminum work with. I am starting with 1m x 1.6m bed from 60x60 heavy extrusion and would like to use a Dewalt router for spindle.

So far i was hoping to use:
X-Axis: 20mm profile rails with 20/5 screw
Y-Axis: 15mm profile rails with 16/5 screw
Z-Axis: 15mm profile rails with 16/5 screw

Driver: Gecko G540
Steppers: 640oz ?
(My knowledge of efficiency/torque etc is severely lacking so pls help here. I would however like to rather go big on the control and motor's in case i want to increase the size of the frame and gantry)

I think if i have a clear idea if the above will form a good build, the rest of the items will fall into place.

Please give your opinion on which items is weak/overkill. I'd like to end up with a balanced system that should last a few years at least.

Many thanks in advance.