Do they sell charcoal ?

I doubt they have any. This is the time of the year it shouldn't be at the back of the store. Instead it must be well exposed with all the barbecue stuff.

Yes charcoal is always in the back of the store near the water.Ask a sales associate or mgr on the floor

At this time I wouldn't know! I haven't visited that Costco since my last visit. Good luck with the floor Managers if there is any to be found that knows anything. :/

Yes

I didn't see it last time when I was there, I suggest calling the store to check their inventory.

I don't recall seeing any.