Nails

Question

Kavod HaRav: I grew up learning these three concepts, and now that I am learning to question certain things (thanks to the Rav and this site!), I was wondering if these were halachot, minhagim, or have no basis whatsoever: 1) One may not cut their nails on Wednesday (and I recently heard Thursday??), because the amount of time it takes for nails to fully grow in would fall out on Shabbat, and we don't want to come to cutting our nails on Shabbat. Isn't that a little far-fetched...and doesn't everyone have a different rate at which their nails grow?!? 2) One may not cut both their fingernails and toenails in one day, because a dead person gets both their sets of nails cut after they pass away...is this superstition? 3) One may not cut their nails at night...i don't even know why this is so. Thank you so much!