1) The stun could be removed and i'd be a happy camper.
2)Agreed
3)The buff isn't that bad actually. I can always tell i'm moving quite a bit faster than everyone else. But it's hard to really see unless you're next to someone running at normal speed. I don't think it'd be bad if it was a little faster though.
4) 1 or 2 seconds probably would be fine. All it would really do is eliminate the need to stack extra skill speed just to use true strike.