She needs to register with a separate email address. If you use different browsers, and have a dual screen setup, you can have both accounts going at once on the same computer, or perhaps she has a computer of her own. Be careful, however, to keep your interactions balanced, because "push" accounts cause a lot of trouble.
There's currently no way to control where you'll be on the map, but other than Trading it doesn't make much difference anyway. Pick the opposite race, so that you'll have the benefit of similar, but substantially different experiences. The building orientations some of the tradeoffs differ between Elves and Human, and of course the Elven cities are a lot more elegant.