The pump will be 120V I would think as even the UK ones are and we usually use 240V here.
I have used the main contactors in my retrofit and use them to switch on the oil pump when the spindle is turned on. I didnt bother with the float switch, just bypassed it, but now I think of it it would probably have been an easy enough job to wire it into the contactors feed circuit. As I will be the only person using the mill I considered the float switch not needed as I check the oil level daily.
The pump works by gearing and when power is to it the gears turn and after a while the plunger is operated and a shot of lube gets pushed out. The plunger can also be operated manually (if the gearing/cam is in correct position), this is usefull for priming the system.
Hood