While this is an interesting prestige class, I'm not sure it is fundamentally playable. Not being able to speak or to use weapons except for mimed weapons would make playing difficult.Telepathy isn't speaking so there is a way to bypass the "speaking" clause.

Sure you can mime a sword but can you mime a +2 flaming sword? I wouldn't think so. Furthermore, I really think you should eliminate this sentence: "He has no belongings, and no weapons. He only has what he can mime." Unless you force mimes to wander around completely naked, they should have belongings, especially since it means they don't have spell components. Not having money and only being able to use mimed money will surely lead to trouble. The gp that disappears is fun the first few times. After that, it will stop being fun and just be annoying. It's too restrictive. Maybe limit them by Vow of Poverty or something.