A: Anything but a Christmas sweater with seasonal appliqués—they're dead, they're cliché, they're over. Use the money you would have spent on one to buy an extra wreath, but don't wear décor on your body.
Jeans are appropriate if that's what you and your guests normally live in. But wear darker, dressier denim—no weird washes or sloppy fit—and upgrade it with sparkly jewelry, a rhinestone belt, and a cute top like a sequined sleeveless shell, velvet blazer, tuxedo shirt, or white satin poet's blouse (you can even add a great apron for kitchen duties).
The nice thing about being home is that your shoes don't have to go anywhere, so they can be really silly. Get out those sexy mules or ridiculous teetery heels that you never wear! Ballet flats, of course, are a little more reasonable as well as chic and fun.