I'm a horn player too. Regards single vs double horns - the answer is very much like choosing a car. If you want to keep up with how people play in the 21st century, then you NEED a double horn. Modern double horns tend to be wider bore and can produce more noise, so for pieces like Wagner and Strauss, etc, you can compete with the huge string sections. Playing on the Bflat side is useful when playing high notes - you will find you split fewer of them. You can also get single Bflat horns (for people whose arms get tired), and double Bflat/high Eflat. You can even get triple horns, which combine F/Bflat and high Eflat. I wouldn't recommend that unless you have plenty of money (the cheap ones are dreadful to match tuning and timbre) and you're an olympic weight-lifter (you get almost 3x the pipe work).
If you like playing pieces from the early Romantic period, then you single horn is probably still good. Pieces like the Franz Strauss horn concerto go better on the F horn for fingering, aren't so demanding at the high end of the range, and don't require the power of sound. Richard Strauss no 1 will work ok this way (he wrote it when he was quite young), but no 2 is definitely in the modern horn school. Both Strausses wrote quite a bit for horn, which you could use for your recital.
If you like a bit of fun, see if you can get hold of a copy of Punto's concertos. Try to play them on the F horn, with and without valves. It will make you think differently about Mozart's and Haydn's concertos, and Beethoven's sonata. You should also try the Mozart horn duets
(Fabrizo has made lots of instrument combinations for these, so you might be able to get a pair of transcriptions that work flute and horn. Alternatively, this is a good set of pieces to get practice in for transposition! Make sure that the part that you play from is written in C, and the transposition will be easier.)