Good stuff, but coming from an RJJ affiliate, there are important details I'd add about the flower sweep.
The lower you can grab on the pants the better. It creates a longer lever, and the pants are just easier to grip towards the ankle. Usually getting the pants grips involves doing a side crunch in to get a monkey grip at the ankle. Now when you kick the leg, you also pull pant leg to you and then stiff arm it up and across your body.
Once you open the guard and bring the foot down, hip escape slightly to the side of the down foot. You essentially force the knee in the butt position, weakening their base to that side, and by angling your hips, you're able to create a more powerful arc with your leg when you swing it for the sweep.
On another note, my favorite follow ups to the free arm post are: triangle (catching the posted arm inside), omoplata on the gripped arm when they try and rotate back to center, and hip bump into them while still controlling the sleeve to finish the sweep to mount (which has the back take, triangle, omaplata, belly down armbar options if it fails).