Cool stage moves and attire while singing??!!?

Do whatever works for you. If you can walk around then that's great. if you need to stand still to get the best result out of your voice, then it's better to do that. "a thousand miles" is your typical nostalgia pop ballad so go standard in your wardrobe: plain t-shirt and denim shorts/skirt/jeans with perhaps a sequin belt or other statement piece.