It's too pretty to crack and put into a Dansco. It will turn full brown and loose most of the color. Save it and buy something raw that matches the look of the other coins in the Dansco.
Nope. I checked the diagnostics for the proofs for 1910 the other day and it didn't match the tell-tale signs, which are pretty clear cut for that date.
I think I'd keep it in the holder as well. There are plenty of raw coins to choose from for the Dansco.
Do you see any flow lines above IN GOD WE TRUST or E PLURIBUS UNUM? Every MS example has flow lines above those. Check them out and see.