Yes to the top question.
Not that thick to the second question - though it depends on how it has been pressed - softly and there is a very thin layer, very hard and the layer is thicker. However, the density of the willow comes into play and that is when it begins to get complicated.........and beyond my brainpower
I refurbed a bat a long time ago where the bloke requested for all the cracks to dissapear, i told him he mighty be left with a bat that would be less responsive but he didnt seem to care........his bat turned from a decent GM Purist into a unresponsive blade that dented quite easily and left big seam marks in.
People will often refurbish bats to 'look' good - but this can be a little risky as, like you mention, it is possible to remove that pressed layer.
This is just me experience of this though, others might have completely difference opinions......im waiting for Andy to tell me i've got it all wrong