Sounds like it's set up for 1/2-10 single start with inches as the native unit.For example, the "Steps per" are set at 20000....? I don't understand how this could be steps per mm...?
4000 steps/unit is correct.
You'll want the accel higher, but leave it at 4 until you figure out your max velocity. Once you set the maximum velocity, then start increasing the accel until you find a safe number. Could be anywhere from 10-30, maybe more.
Step and dir pulse should be left at 2 per Gecko's recommendation. It's the length of the step pulse, in microseconds I think.
I'm not a big fan of using a "standard" .xml file, unless it's for a specific machine. When it can be used on virtually any machine, the only settings that you know will work will be the pin assignments for the motors. (and the pulse width, I guess) Just about everything else can be different.