Would be nice to know what year Focus you are looking at.
I pull a 2013 HB with the 'Select-shift-6 speed' trans. This is a twin shaft, double dry clutch system that works well. Yes the lurch you speak of CAN happen, though seldem does. On the dash you have a 'P R N D S'. S is for manual shifting by pushing rocker switch on side of shifter. Up side shifts up one gear each time you operate it. Down side shifts down one gear each time. I have used it in the mountains to downshift for speed control.
I must disconnect the battery when towing (installed cut off switch) and power my RVIbrake2 with a J&C 660 jump box. Lights are powered from the coach.
As with any toad, you need to follow the owners manual.
jim