I think your natural color would look beautiful on you. Why not try to get a color as close to that as possible and then enjoy it without having all that upkeep? You'll have plenty of years for dying once you start going gray.

As for the length, I think you have one of those rare faces that looks gorgeous with hair pulled back, like you wear it. So whatever style you choose, I think you should still be able to wear it in a pony tail, etc.