Oh Wow Bill! You are such a beast and those are excellent questions! Since you are a Running Demon, you could be in a movie and your character would be Beelzebub, played by Billybob Thornton!
You are spot-on. Ground contact time is one of the keys of better locomotion. Foot and ankle strength, and actually transient stiffness, is what we need to hit the ground by snapping down, quickly have a force exchange, and then pop off back up into the air. This is effected partly by thought and focus, but also enhanced by all the hopping, jumping, and footwork we do in the Tribe. We also want to be aware that maximalist, or marshmallow shoes tend to slow down GCT in most runners. Training barefoot on grass counteracts this.
Also a good delineation on aerobic base or recovery training versus power intervals. Most of your runs should just be easy and slow, building that 70%-ish base of fitness. Then, in the power intervals, like you described, mixing walking uphill with charges, just go ham. 90% or more effort especially if it’s under a minute. A gasser! Just be sure to recover adequately between reps so you get the proper power training stimulus.
You are the man. Thanks for your Q’s!