When Tuvok was asking Janeway for help he mentioned that he was considering asking another Vulcan on board…there are other Vulcans on board?
Yep, there's at least one -- Ensign Vorik, whom you will meet in Season #3 and periodically thereafter. The actor who plays him is Jeri Taylor's son, so she obviously managed to shoot him the occasional gig on the show ... But he's quite good, too.
Oh, and as for the darkness and candles? Yeah, that's a cultural thing, apparently. Vulcan zen. I'm sure whatever safety regulations there are would be overridden by the Federation's rules on permitting certain cultural celebrations provided any safety issues are handled responsibly (blow 'em out before you go to bed ...). At one point B'Elanna burns some incense that the Captain (I believe) remarks should set off the environmental controls ...