Hi Shell Stones -- congrats on your ceiling remodel ! If you use dimmable LED recessed lights, then even if you have "too many" you can dim them. But if you have "too few", then you cannot get any more light unless you install another light source.

Do you play Go ? ( is that the reference for "shell stones" ? :)

Approximately 3 feet apart depending on whether you are planning on having floor lamps.