Do you think this is a good Christmas dinner?

That sounds amazing! Good for you! Your meal is very well rounded. Just to make it a little more 'gourmet', try swirling a couple dabs of butter into your reduction off the heat. It makes the sauce have a great glossy look and feel. Good luck and Merry Christmas!

Everything sounds pretty good. The only change I would consider is a balsamic reduction rather than a white wine but that's trivial. To really top it off place the loin off the bottom of a pan with a rack and use the dripping for the mashed potato gravy that is where you can use the white wine to deglaze the pan. Now if you can plan well ahead for that reduction to truly reduce a base it takes a long time on medium to low heat..

Yes I do! I think it sounds divine and I am so impressed you are going to make all this at 13!! Don't do any dishes afterwards. After that kind of meal you are done doing any chores for the rest of the day. Merry Christmas!!

I would rather see another couple of vegetables and skip the bread, I don't generally have two servings of starches, although I do know for many they do that not just with potatoes but rice and pasta

Chetak

Sounds wonderful, though I would add another vegetable, for nutrition as well as for colour on the plate. Glazed carrots, perhaps, or roasted tomatoes.

I think it sounds great!

I think you should go with the cake, it will look more festive and make a nicer presentation than the cupcakes.

Perfect! Sounds like you are on your way to being a great cook.