im just gonna take a simple explanation for the movement of the ribbon. pretend that the shockwave from the explosion is a pond or lake. the ribbon is a smooth shaped rock. when you throw the rock at the correct angle to the water it will skip across the pond. now while its still going the same general direction of how you throw it, the skips cause it to go a little further or higher or at a slightly different arc into the pond.
Well, first of all, there are no shock waves in vacuum. That's a common fallacy in SF. Second, even if there were, they'd travel slower than the speed of light. So there's no way the destruction of a star would instantly affect the course of a starship or anomaly light-years away. The only way to rationalize things like the stellar explosions affecting the Nexus, or the explosion of Praxis affecting Excelsior light-years away, is if we wave our hands and assume there's some kind of "shock" that propagates FTL through subspace and affects subspace-connected objects like the Nexus or starship warp cores.
stop bringing science fact into the context of a movie that uses made up elements. for all we know there could be trilithium and when it is combined with a star and heats up to the point of explosion it expands out like a popcorn kernel. the point is, when dicussin the future and future elements, technology, materials and the like you can basically make up anything you want because it cant be proven false.