Ok a few things,
First is set the kernel speed to 25KHz, it can affect feedrate readings when using the SS, actual feedrate will be correct, just displays wrong.
Next set the E-Stop up to a port and set it active low if you dont have one, that way you wont get the annoying message.
You seem to be set to pulley 4 according to that xml so set to pulley 1 or best bet is set all pulleys to the max speed you will be doing on the spindle.
Your acceleration seems high for a stepper spindle and is a likely cause of you stalling when you command a high speed, I would try 10 for a start, remember its revs/s/s as opposed to a normal axis being units /s/s
Go into the SS plugin and set the pulse width to 1.5, with it set at 5 you will likely saturate the step signal as there is no divider on the spindle signal like there are on the axis.
Hopefully these will sort you out, if not I will check in the morning, its 1:30am here so I better get some sleep
Hood