How about 1 and 12 for the Dax/Julian/Jadzia asks?
1: who sleeps/sits in the middle?
Given Dax tends to live inside of Jadzia it's a bit complex, but proper ritual can let them transfer hosts for a short period so sometimes they'll do that and have Dax go into/around Julian and then he's cuddled in the 'middle' next to Jadzia and with Dax sort of manifested/wrapped around him
12: who has to kill the spiders? And who refuses to even get near them?
Trill (or at least Jadzia) have some biiiig allergies/phobias of insects/spiders (as certain insects on Trill can cause serious issues with symbiont bonding if I remember The Circle episodes correctly) so dealing with spiders tends to fall to Julian, as Jadzia and Dax quite sensibly refuse to go near them. Rodents and other small mammalian pests that find their way in/around their quarters do get scarfed down Dax's toothy mullet though.