does anyone know what Mr Beaver's personality is like and his role in the story and any strenghts and weaknesses he may have?

Mr. Beaver has a pretty minor role. I'm reaching back in my memory here. I recall Mr. Beaver fills the kids in on the goings on in Narnia. He appears brave and there is some comic relief between Mr. Beaver and Mrs. Beaver. The children are apprehensive but Mr. Beaver explains the gravity of the situation and is willing to guide them to a point. Mr. Beaver is not a hero-figure but he is willing to risk everything to hide the kids as the shadow of the white witch clutches Narnia. He also makes a damn good Beaver dam!