Digital DC Variable Speed Drive for spindle control

Gentlemen,

I'm in the process of changing the old Fanuc controller of a medium size bed
lathe to a new control using mach2 and Geckos.
I already setup my Z&X axis, and they are working fine, now I'm getting to
the part of spindle speed control, the spindle motor is a 11 Kw BBC
DC motor, which came with its old speed controller which I'm scrapping.
I'm thinking of buying a new digital DC variable speed drive (inverter) for
the motor like the one in the URL below:
http://www.controltechniques.co.uk/products/mentor_intro.htm#Benefits
I know it's a bit expensive, but I'm planning to use the lathe for
production work, now I was wondering of the way to control the speed drive
from mach2:

- Can I send step & Dir pulses to the speed drive as it has digital inputs.
- I have a 1024 PPR encoder attached to the spindle, do I send the encoder
pulses to the speed controller for feed back.
- If so, can I rely on the speed controller to keep a constant speed, for
threading operations, or do I have to take an index pulse to mach2 to do
threading.
- I think mach2 does not support serial communication to speed drives, am I
correct.

- If non of the above is feasible, what other options do I have to
communicate between mach2 and speed drives?

Please advise,

Mina F.

P.S. I apologize for multiple group posting.