1)For crying out loud, you PAID for her service!
2)Depends on how the letters were drafted. They should be concise and eye-
catching in establishing the reference's credential, not too much, but
certainly not less either. Let's say if a Nobel laureate says your Work is
great, he's providing an objective evaluation. But if he says You are
awesome, that's dubious.
3)If your adviser is a native English speaker, writing grant proposals all
the time and a well-published author, you should follow his suggestions like
Bible.