LRD in what way have the 12 Days become the ones leading to the 25th, sorry? (Am not being snarky, am genuinely confused...)
I love that Carols From Kings has been being broadcast since 1928 (apart from in 1930) so for many people listening to it - even/especially when Far From Home -signalled the start of Christmas. Christmas Carols are fascinating in & of themselves, too: the language, imagery, how carolling & wassailing traditions have become intermixed, local carols, the simple fact of the earliest known carols coming from the 4th century AD.
Tunip & LRD I love the idea of the Lord Of Misrule, too. Not sure I'd be so keen on the reality of it, mind you
I'm more fascinated by the Boy Bishops, though, I think: wonder how long that tradition would've survived were it not for the Reformation. Assume you were meaning the tradition of inocentadas & other sillinesses when talking about Holy Innocents as a bright spot: the mass slaughter of boys aged under 2 years (& the solemnities of the commemoration thereof) not being especially jolly 
I get a little bit frustrated by people who insist that Christmas is actually totally a Pagan holiday. Obviously elements of Saturnalia & Other "Old Religion"'s ceremonies & celebrations were included, but that is Not The Same Thing. Oversimplifications like that make my head hurt.
All the St Nicholas' Day stuff fascinates me, including the fact it didn't, for whatever, reason, take off in the UK. Similarly, the C20 encroaching of Father Christmas (by whichever version on his name) into the Christ Child's Bringer-Of-Presents territory is v interesting.
I love the stories & traditions linked in to the Christmas story: like how you mustn't kill spiders because a spider saved the Holy Family from soldiers who were searching from them by spinning a web to cover the mouth of the cave in which they were hiding in just one night. Or how the rosemary bush came to have blue flowers, or the stories of Baboushka & La Befana. When I was very wee I thought it quite possible animals really DID all kneel down & pray in Latin on Christmas Eve 