1) Blackish side: all traps eventually turn black and die. Don't worry. It's natural. New ones come up from the center
2) Bright sunlight for at least 8 hours is good. Windowsills work fine as long as its providing good, strong light. A north window wouldn't be enough...a southern exposure would be good. Outside is best.
3) To grow well: lots of sun, kept wet or moist with PURE water, don't trick the traps, don't fertilize, grow in nutrient-poor soil
4) Bugs: I'd let it get its own bugs naturally but that's my preference. If you do feed it yourself: only live prey, must fit comfortably inside trap
5) Closed empty traps may have been triggered by rain, a fast bug--something touching the hairs inside. They will open back up
6) You can remove blacken plant material if you like to keep them neat and clean looking but you don't have to.
7) I do not recommend tanks for growing VFTs but that's my preference. I found they do better outside in a plastic pot