Haven’t read through the entire post but here is my .02 with your questions.
Improving Front Side Mechanics – Show video and educate on why it is better. Give cues to get them in the right positions.
I feel strongly at the high school and club level that you should cue and it makes them better. This would be after a powerpoint and showing film of fast people and how they look as well as using cues.
My cues for max velocity which may or may not help with front side mechanics. I give one at a time through 60m at 80%.
1. Toe up
2. Step over opposite knee.
3. At toe off don’t let foot dangle back there, be 70% frontside to 30% backside.
4. Hips are a bucket of water dont allow them to spill out the front. Tuck hips under. Squeeze butt and abs.
5. Get your lower back flattened out. No curvature in.
6. Get hips as high as possible while up tall.
7. Get knees to parallel to the ground.
8. Drive knees up fast as possible.
9. Drive knees down and dont let gravity do it for you.
10. Strike ground with foot so that you bounce off of the ground.
11. Keep shin perpendicular to the ground so that you are not throwing your bottom half of leg out in front of you.
Obviously many of these are the same but I use them all because some work for some kids while kids will react to others more positively. I have more for the upper body too but I am not sure if it will help with frontside.
If you are strict with the warmup with watching it and making sure the kids are hitting the right positions there can be cross over especially if you connect it later on when working running mechanics with the athletes.