Quarrying is indeed a good way to find ores, but it isn't the only one. I'll reveal that certain avenues of research also provide chances to receive special resources, and one of the good random events can also grant them. There might be other ways.
The primary use for leather is leather armor. Leather clothing can be created as well, but it indeed doesn't stack with normal clothing. You could provide leather clothing if you don't have enough wool for your population, though.
The Sidhecraft trait was meant as a minor bonus from the start, and I was a bit surprised you considered it so powerful at first, actually. However, much like Trade opens up new options, other research may open up more and different options for everyone. That said, while I have some ideas what might happen and what might be gained by certain actions, I'd like to be the players to be the driving force behind what transpires in the world.
Neyvn: I'm finding that 5 players is a nice number, but a 6th player isn't out of question, if the other players don't mind. I'll have to figure out your starting position, though.
Haika: Note that a labor unit isn't a dedicated military unit or explorer unit, and thus might be ill-equipped to handle exploration or danger.
Regarding luxury: Note that while shrines only provide enough luxury for 10,000 people (or 15,000 for Haika), you can mix and match luxury from shrines, clothing, excess food, and whatever other luxury resources may exist. So if a shrine is complete, and you have clothing in your warehouse, you only need 0.2 or so clothing to increase morale, or use 1 food. That said, food that is put into your granary isn't used automatically - I'll assume that excess food is generally stored (if a granary is already built) for hard times. Also, in the previous turns, the excess food hasn't been sufficient to raise morale.
Finally, with Easter and the potential DF release around the corner, I suspect that things might slow down a bit. Don't worry much about getting turns in late for the time being.
We have all the turns in for year 3, though I'd like to give evilcherry the opportunity to write some turn flavor first. So far, I find writing the turns much more enjoyable if I have some flavor to bounce my writing, meager as it may be, off of.