Hi, and welcome!
Loads of choice for mirrors. Ebay should have a good selection, and there are plenty of pics of people bikes on here for inspiration, so look at pics and ask others.
Not sure about tail tidy, as I have mine standard. Lots cop the tea tray off (do a search for info), but you might have to cut the cans down as well as they look quite long, otherwise you get the wheelbarrow effect.
As for extras... carbon... then more carbon... until you can afford no more!
