Unfortunately it's too late to do the black pop of the grain, unless you want to sand it all back completely and start again. What you'e done looks great, and if you're happy with it, don't second guess yourself! This build is all about you, and what you like. Don't go changing your mind based on other opinions.
In regards to the binding, I found the best finish is to scrape it with a nice clean and sharp stanley knife blade. There are a number of videos on Youtube on how do do this, even one from a Gibson builder.