Re: Question on masturbation...
Hell yeah it's normal! Babies even play with themselves! Also, concerning ejaculation, I think you're pretty close. I started REALLY EARLY, like I first came a month before my 12th birthday, but I was an "early bloomer" yay! For you, I would guess that you'll be able to ejaculate in the next two years at the latest (since you're right on track, unlike I was). Heck, you might start this year! But don't be bummed if you don't; 14 or 15 are perfectly normal ages (though I think 16 is getting pretty late).
As for cross country, I have no idea how that could affect your height. If anything it's just giving you more muscular legs! Are you just short, and want to be taller? Ya know, that'll take care of itself too.