Electronics ... headache, questions...

Steering in the direction of 65volt dc PSU, 80volt drives 500 Watts or so will do....
And will keep me on track building a reliable machine...

But....
I dont want to go OTT, but dont want to under engineer either.

So after reading a lot of stuff i still can`t decide what voltage PSU/Drivers i would need to run my machine well.
Online-electronics-kits all list 36volt-PSU and 50volt dirers, that is confusing.

So here are a few questions.

The best guestimate i have for the total moving weight of the gantry is about 65-70KG
(including steppers, rail+blocks z axis 2.2kw spindle, steel, alu plate etc)

The best guestimate i have for the total moving weight Y+Z = +/-35 Kg.

The best guestimate i have for the total moving weight Z = +/-20 Kg.

X/Y 2:1 stepper : 1610 Ballscrew
Z 1:1 stepper 1605 Ballscrew

Main questions:
Q Y-axis: 2X slaved Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 65-70KG
Q X-axis 1X Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 35 Kg.
Q Z-axis 1X Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 20 Kg.

Q What is the real advantage of a DIY Toroidal PSU, just noise?
Q What DC PSU voltage should i be running?
Q Stepperdrivers, Leadshine? 50-80Volts?

Q 1 or more PSU`s?
If 2 PSU`s. what setup, like X and Z on 1 PSU,
and the slaved-X set on 1 PSU? Or mix it up?

I think for now my initial PC setup would look like this for now.

- Dedicated networked windows 7 PC.
- Mach 3/4 through PP.
Q 64Bit or 32Bit?
Q PCI or mainboard PP`s?
Q PCI PP, what to look for when buying one.
Q Any Minimum video card requirements?
Q Maximum length PP cable to BOB.


Thanks in advance, Bert