XY-8080/Controller/Motor Questions

Hello, its me again with the XY-8080 tables + Oregon Micro Systems
controllers. Thanks to everyone for the help with software ideas.
Well, I've learned a little about steppers, and I had the guts to
hook a controller up. These controllers, MD10A microstepping (10
uS/Step) units have +24-60 for motor power, Phase a,b,c,d (to be
hooked up "bipolar"- the motors have 4 wires). There are also the
following connections:
Control
direction
Step pulse
Logic +5
current set
Gnd

I figured out that the direction and step pulse are the LED sides of
optoisolators, so grounding them does the job. I think "control"
might simply be a "disable motors" hookup.

There is a "current set table" as follows:
Series Parallel Resistor

1.5 .75 12k
2.0 1 15
2.5 1.25 27
3.0 1.5 33
3.5 1.75 47
4.0 2.00 68
4.5 2.25 82
5.0 2.50 120
5.5 2.75 180
6.0 3.00 270
6.5 3.25 460
7.0 3.50 3.3M


The motors are rated at 1.7V / 4.7 A.

I wanted to test these out as conservatively as possible. I hooked up
a junk AT power supply with +5 for logic and only +12 for the motors.
Again, being conservative, I selcted a 15K resistor for the current
set. powered it up, and the windings were energized. I grounded the
step and direction with a bit of solder wire and the motors moved
like they should as I moved the solder wire across the screw head.
Later, I worked up the nerve to go to 33K. Still OK, and still not
even slightly warm.

A few questions:

1. I assume that this controller does tricks and probably has a
sophisticated ASIC or something like that soing some sort of PWM, or
maybe the pulses are stepped like a sawtooth (high voltage to move
the motor, then back to something lower) although I didn't look at
the output on a scope yet. I can't look inside the drives because the
package is an integral heat sink and is potted. But how can I set
this up for maximum power without letting the magic smoke out of the
controller or burning up the motor.

2. I'll probably get a proper power supply for this set up. But how
many amps would be enough? I assume that the drives/controllers have
anti-back EMF stuff built into them, but I think that switchers just
dont like inductive loads (and they certainly don't have the brute
force reliability of a good linear). Linears are getting harder to
find and expensive. Any experiences?

Does the power supply for the motors even have to be tightly
regulated? would a big-a** transformer, and a very beefy bridge and
giant cap do?

2. Assuming that I'm not going to be using these for any heavy-duty
purposes (drilling/routing PCB's), is there any
advantage/disadvantage to running less than full power. I assume the
risk of dropped steps and lower max speeds is there.

Thanks in advance. I hope these questions are not completely stupid.
BTW, you might be interested in my web page concerning stepper
motors, computers, and telescope control at:

8080geek.freeservers.com/touch.htm

I'm using an industrialized PC that is available for a good price on
eBay, and I figured out some useful stuff about it, including how to
hook up a hard disk inside. I'll probably use one of these ultimately
as my G code interpreter/driver.