If he goes to everton he can kiss his 100% guaranteed to be england #1 keeper spot goodbye. Maybe he was better a few years ago and has gone down hill, it happens, look at iker casillas he was unstoppable for so many years then just lost form a few years back.
Every goalkeeper will have their peak and soon after that their form will gradually gets lower , it is not really a problem because he is still much better than most averag goalkeeper on the premier league. Sometimes it is not about goalkeeper alone, if the defenders are bad then it will makes the goalkeeper looks bad
i don't think so. Just remember Edwin Van Der Saar, who's retired at the peak of his career in the fifth decade of life
Take a look at Bufon..