The rod weight usually indicates the lure weight it is designed to cast, light, medium, heavy, basically the stiffness of the rod. A medium action to medium heavy rod is fine for bass and walleye, a bit on the light side for bigger pike and possibly not suitable at all for Muskie of any size.
More info is needed, have you used casting reels? or spinning only? Casting reels are usually preferred for big pike and skis some practice may be needed if you haven`t used them before.
Line choices are sort of endless, it depends on what your comfortable using and what your fishing for. A line for walleye may not be suitable for bass in cover or pike and skis. And ya it`s easy to go overboard on the price of equipment.
You don`t need the most expensive outfit to catch fish, just good quality reliable tackle.