Growth is usually a fairly early change, but it's not something that occurs all at once. Generally speaking you'll have several growth spurts over the course of 2 years. Statistically, that is when the majority of growth is done. You may still experience growth after that, but generally not anything significant.
You can not pee from it because your urethra is not inside your clitoris. Your urethra is between your clitoris and vagina.
You clean it just like you clean your junk now. Water, washcloth. Avoid anything that would irritate the skin. It's not terribly complicated. Ends up looking like an uncut micropenis, so you could google cleaning under foreskin if you want tips on that.