Lead Developer
The steps in the post I linked to deals with everything, including transparency.
Making the navigation sticky like that does require some custom work, but all the steps are outlined in that post – no way around them at this time. You could start off with one of the child themes listed in that post, and then customize them to look different in the Customizer, while keeping the sticky nav?
I am working on an add-on which will have that feature, but it probably won’t be out for a bit.