Great work Dave,looking forward to seeing the finished article,dont worry mate about the airbrushing i'm sure you'll handle it ok,i was nervous about using mine a couple of years back but they're great and the finish is so smooth,horses are ideal for practising with larger areas to work on than figures paticulary for the musle tones which are prominent on horses.
Dave Andrea press have a good book about painting horses which i found an interesting read,anyway good luck mate.