Regarding 2., it's not that simple, especially if you're young and are given puberty blockers (which have nasty side-effects and are hideously unhealthy, which is why only post-adolescents should consider this stuff, not pre-adolescents), or undergo sex-realignment surgery or drugs.
It's a major commitment, and really, one can never go back from it, from my understanding.
puberty blockers ≠ hrt, puberty blockers have basically no side effects or anything like that, and as soon as you stop, your hormones will go back to normal lol
additionally, transitioning doesn't require sex reassignment surgery. A lot of trans folks wont do it because that particular bit doesn't cause them dysphoria (like me), and even if you do want it, the process is very long with the ability to change your mind at literally any time. People who get the surgery genuinely want it
It's a major commitment, and really, one can never go back from it, from my understanding.