What a fun thread OP!
What does he bring?
In our house he fills a stocking and brings one additional "big present". The big present should be something from their lists.
Other presents are from the relatives who bought them.
If he brings a stocking, what is in it?
It should be enough things that the stocking looks nice and full and exciting. You can buy any size of stocking to suit your taste/budget.
Last year DD had: a collection of small shliech type toys, sunglasses, hair brush and bow, cheap bracelets and rings, sweets.
DS had walkie-talkie watch, Invisible ink pen, card game, some other "spy stuff" I can't remember now, sweets.
How does he deliver the presents?
He comes in a sleigh pulled by reindeer. Traditionally he then arrives through the chimney. If you don't have a chimney you can make something else up.
What is this magic everyone seems to be talking about anyway? Can Santa do magic? Do the elves do magic?
Magic is your answer to any awkward questions about logistics. Its my understanding that Santa uses magic to increase the carrying capacity of the sleigh and to stretch the available time.
Do all the presents get manufactured by his elves or does he buy them directly from toy manufacturers?
Elves make them.
What happens in a grotto?
The children meet Santa and he asks them what they want for Christmas. After this point you can tell the kids that last minute updates to the list are off the table. They already told Santa what they wanted.
Is the Santa in the grotto the real Santa?
Mine believe it is!
Where did Santa come from and how old is he?
He's ancient. He comes from the North Pole.
Is it generally accepted that Mrs Claus exists or is that something from American movies?
I like to think he's got a special someone.
How many elves are there? Are there any special elves?
There's a factory full of elves. They have some special ones. Notably the shop steward and the Elf n' Safety rep. (sorry)
Do the elves venture out of the North pole? Do they do anything else apart from on a shelf and manufacture toys?
In our house- they just make the toys. They certainly don't venture into the house and move around various shelves. Not going there. Nope.
What does Santa like to eat and drink?
He likes whatever Christmassy thing you have to hand. I do a mince pie and a glass of sherry. The reindeer like a carrot.
How does he enough time to visit all the children in the world?
Its magic. NASA have a cute app where you can track him across the world.
Does he live in Lapland or the North pole?
North Pole
Does he use technology or is he low tech?
I imagine his factory is equipped with all the modern machinery needed for moulded plastic toys.
Who delivers Christmas Eve boxes? Are they a generally accepted part of Christmas now and does everyone do them?
Christmas Eve boxes are optional. I don't think anyone supernatural needs to bring them.