Hello there. When talking about 50ms, it is indeed the speed set in Corsair and AHK. I pref AHK myself and have scripts made for 50ms all the way up to 275ms for both my “Q” and “E” that I use.
So in my case I start my Q-50ms script and E-50ms script in AHK for this macro.
If its 1-2 mobs I just hold down my Q button for ST DPS, and if its 3+ mobs I hold down my E button.
When it comes to GSE itself its not much settings to do unless you want to modify the macro someone made to deactivate stuff you want to control yourself. In my case that is Divine Toll normally so I just hook off the “Disable block” button 
If you look around here on the forum a bit you will see @Elfyau have made a great post explaining how MS works and how to set it up properly
Here is the link to that post: