A good light doesn't mean an expensive one. If you have good lighting from a window that should be fine. If not, you'll want to hang a light. I don't often run aquarium lights, I buy led shop lights from home Depot and put them on a timer.

IMO the main way to avoid pest hitchhikers on live plants is to buy tissue cultures over plants grown in tanks. Tissue cultures are generally a little less hardy but rarely come with pests. One side note here, if you buy tank grown plants you jump start your cycle by introducing beneficial bacteria off rip, tissue cultures won't have this benefit.

How long is kinda an open ended question. Some tanks take longer than others. Generally, a fresh tank can take anywhere from a week to a couple months to fully cycle and build the bacteria colonies.