That is an unbelievably wonderful airfare!
Your priorities are all down in Andalucía, but you are flying in and out of Barcelona. Barcelona itself is great, so I hope you plan to spend some time there, as well. There are also great smaller towns in Catalunya: Girona, Cadaques, Sitges, Besalu and others.
You can get from Barcelona to Seville in about 5-1/2 hours via AVE train. There are frequent departures. Most require one transfer, but there's one morning train and one mid-afternoon train that do not require a change. This will probably be about as fast as flying, because you don't have to deal with getting to and from airports, etc. Driving that distance would be much, much slower, and I wouldn't do it unless I was planning to make stops along the way. Much of the countryside around Madrid is unexceptional.
Spain is a large country, and I don't think you have time for Barcelona, a bunch of destinations in Andalucía, and a lot of wandering around in the middle of the country (much as I love Toledo and really like Segovia).
For your other long travel leg, you'll probably want to fly. You can explore options on skyscanner.com. Perhaps a flight to or from Malaga would work. It would be better to do your Barcelona sightseeing at the end of your trip, but that would mean a long slog down to Andalucía on your arrival day, and you really shouldn't buy the train ticket ahead of time. If you end your trip down in Andalucía, you'll need to fly back to Barcelona the night before you return home. Do not try to take an early-morning flight to BCN to catch a transatlantic flight; that's too risky.
For planning purposes, I like to check schedules on the Deutsche Bahn website. Spanish buses are quite comfortable. You could benefit from having a car for at least part of your time in Andalucía; it will make seeing the white towns a lot easier.
It is a major time commitment to go to Tangier--perhaps the better part of three days in order to have less than a full day there. I love Morocco, but Tangier isn't the best of Morocco. With all the great sights in Spain (10 days wasn't enough time for me in Barcelona), I wouldn't spend a chunk of a 2-week trip trying to get to Tangier.
I would definitely include a day in Cordoba either on the way to/from Seville or as a day-trip from Seville. I think Ronda is a full-day sort of place, but you might use it as a base for seeing the white towns. Seville needs multiple nights. I think Granada pretty much requires at least two nights because of logistics. I haven't been to Nerja.
David's good about suggesting routes through Andalucía, so I hope he'll stop into this thread soon.
