How fast should an 7-8 grade pitcher be able to pitch? How far is it from the mound to the plate?

My sister is a really good softball pitcher. I work with her often. I am a good baseball player even though i have never played on a team. But there was this game at a fun-day at my school where you pitch a baseball and it has a radar. I pitched 44. My dad heard this and decided he would start practicing me to see if i may be able to be a pitcher. I would really love to become a good pitcher. So, what are some tips, and please answer my first two questions.