We live in DC, so she'll be flying out of here if possible, or New York. Looks like everything from here goes through CVG except AMS. Is there a problem booking multi-stop flights to a destination using the benefit (is there a better word for it?) And how far in advance can such a trip be booked?
My bad. I assumed you'd be flying out of ATL. NYC would probably be your best chance of getting to FRA. (Or any of the other options mentioned above.)
RE: multi-segment flights. No, as long as you give yourself the connection time to check-in for the international flight.
RE: advance booking. You can book your flights the first day you have the flight privileges. Personally, if/when I'm non-revving somewhere, I usually wait until the week prior to see how the loads are looking. If you booked your FRA flights two months prior, then come to find out the flight is oversold a week or two out from the flight, you're duplicating work by having to delete old listings & re-list for your back-up options.
All that being said, Welcome! It'll all make sense in July.