lots of practice is how you can tell baby's position, but as a rough idea if you can feel a round part up high if it is fairly solid and doesn't wobble, it is a bottom. If it wobbles, it is a head. As for the position of the babe other than breech or cephalic, I haven't the foggiest.

As for a baby turning after 30 weeks, most certainly they can. Most obs and midwives will not worry unless a baby is still breech past 35 weeks and even then they can turn either on their own, with accupuncture, or with ECV (external cephalic version) which is when they manually turn the baby still inside your womb.