Arriving Edinburgh after closing hours?

Arriving in November when it's obviously going to be quite dark after 6pm. Very likely no tourist sites open at that hour, but I'd love other travellers advice or locals to suggest something intelligent to do - not interested in getting drunk or trying haggis. Would shops still be open? Looking for something educational, Scottish-y, perhaps to see a fountain that might be lit up at night, or other photographic opportunity that I might not have/take time to see otherwise. I am only in Edinburgh 24 hours. I plan to see the Castle, perhaps a museum, walk the Royal Mile of course. Would LOVE it if someone could put me on to an excellent charity shop that might have something cool to buy! Also any useful suggestions on best options (assuming train, but would love to know if there's a bus/coach that's actually better) to get to Newcastle. I would be leaving at 6pm or later on a Wednesday. Maybe a 2-hour trip? Can't tell! A lot to ask in 1 question thanks for the help!! :-)