If you possibly can, wait until after Christmas. (I know! Impatience!) There are just so many things dangerous for a new kitty — poinsettia, ribbons, tape, light strings, breakable ornaments, extra people clomping around stepping on things and leaving the door open so a scared kitty can run out…
After Christmas you’ll have more time to sit quietly and let the kitty(ies) get to know you and their new space.
I’ll bet that in the scene in Star Wars 3 (Revenge of the Sith) where Amidala names her twins before she dies, there’s an outtake where she says, “Luke…. Laura… (gasp,thud)”
Every time we refill our fountain we pull the filters and clean them. There’s a simple plastic one between the bowl and the pump that just needs a rinse to get the cat hairs out, and the charcoal one inside that needs to be backflushed with hot water to remove the ewwww slime. Once a month I’ll take the thing completely apart, clean the slime from every surface, replace the charcoal filter, and run sodium perchlorate through it before I rinse and refill.
Every time I do that, I think of making an Amazon video review complaining about all the places where the slime hides and is impossible to get all of it, so it feeds the next slime ecosystem. How the heck are you supposed to clean 30 degree corners, 1/2 inch spaces between walls, and tiny (I mean, 1/8 inch diameter) hollow tubes?
If nitroglycerin made the symptoms go away, it was probably a spasm of a blood vessel — angina.