1- periods can hurt, but probably not in the way you think. Some girls can get cramps near their hips and lower belly, but some are unaffected. I get pretty bad cramps, and to soothe them i try curling up in a ball, a heated stuffed animal, a warm shower, or some tea. Normally girls don’t get cramps until around their 3rd period.
2- It’s just a sign that you’re growing up! If you feel really self-conscious, try asking your mom to teach you how to shave.
3- That’s not too early, I have slight curves and I’m 12, almost 13. Everyone’s body is different.
4- Yeah, that happens, I can’t really relate with you because I run track and therefore am used to it o guess? About the breasts, if you’re uncomfortable while running, try a sports bra! They are snugger than normal bras and therefore have more support. They make them with and without padding and cups, find what makes you comfortable! I would not advise getting an underwire bra as you are younger and underwire can harm developing breasts.