lights tend to stress my boys out , but some others like the light, it depends on the fish, I prefer some natural light, and when I want to use overhead lights, its in tanks with plants. The 8 hours of light I believe is not for bettas.
As far as hiding spots go , bettas LOVE them. It keeps them entertained and they don't stress as much when they have a good hiding spot
I recommend any cave that can 1) have a stocking or woman's panty hose run over it without snagging and 2) has holes that you can fit your thumb into without getting stuck. Because trust me if there is a hole, the betta will try and squeeze into it lol .
Also You could add silk plants, that pass the panty hose test as well, I like real plants. I would recommend Anubias, I just let mine float, they don't need fertilizer, and just low light (light from a window, not direct) and my boys sleep on them its cute.
Hope that helped!