If you're having trouble soloing you could try taping some riff you made up (be sure you know what key you're in) and try to solo over it. Being able to solo doesn't come easily, it takes a lot of time and practice. Another suggestion for your trouble with playing past the 15th fret is something that my guitar teacher does. When he gets down there he plays with only his first three fingers because he says its less crowded. Also get a metronome thats where you'll get your speed and accuracy. Try learning some licks, after a while you'll start to make up your own and your solos will sound great.