Don't worry too much about stretching vs. non-stretching..or before or after the workout. Just get the plyos into your schedule on a regular basis.
Light plyos are advantageous before a competition or a hard workout during the warmup..and in these cases you may want to keep stretching to a minimum.
But if you are going to skip streching/range of motion (ROM) before workouts then you should have a dedicated ROM session the week where you really get good and limber..and be doing ballistics with exaggerated movements. Otherwise you are setting yourself up to be a cripple.
The one legged jump rope is excellent for lower leg strength. But first start with jump regular jump rope first as you build up the "core" jumps. In general you should gravitate towards 1-legged jumping as it is more neurospecific to the task of running. It also works to improve proper proprioception and balance.
Plyos work specific power recruitment patterns within the muscles without a concurrent increase in muscle mass. This is advantageous to distance runners. We want to be strong and explosive but also light.
The strengtening effect can help reduce injury by increasing efficiency of foot strike. Recovery is also enhanced because the increased proprioception and decreased contact time. That is, your eccentric pounding is greatly reduced. Don't forget power expressed as speed too. Plyos increase your raw speed. They are the ultimate derivative of pure speed.
esmoke