Would a diva cup be the right choice for me?

I can't search out this cup on my computer because I don't want to freak my dad or brother out to see it in the search box and I'm not allowed to erase history. I saw an add for the diva cup in my Glamour magazine last night, and well what is it? I understand that its a cup but does it ever fall out or is that just my paranoia? How much does it cost, how convenient is it, and could I sleep with it in if i wanted to? I am a musical performer and a dancer to I'm going to twisting and twirling upside down all day and moving for upto 5 hours. Is this a good choice for me?