The rated input voltage is 265VAC.
The rated output voltage is 240VDC armature and 120VDC field.
What output voltages does the speed control produce when it has 220VAC input?

This unit optimally runs on single phase 265VAC, and will also run at 220V but with a lower max output (you usually get 80% of the AC supply voltage in DC output voltage). A small boost transformer (240/24V) can bring you up to 265V. A 120VAC supply for the control logic section is also required.

What protection does the control provide against field loss?

The principle behind this design is that from zero speed you have full (120VDC) field supply and as you increase the armature voltage to approx 80%, the field output begins to drop to a min of 50V, allowing you to obtain the full RPM on the motor.

Does the control provide dynamic braking?

Yes.

Will the control maintain a constant speed under load?

As a DC drive you will get constant torque at all times.

Does the control require 3-phase power
or single phase power or can it be run with either?

If you have three-phase AC, you can supply the unit with two legs.