use SetSize... and you just have to do a bunch of checks..
you have to come up with an algorithm for changing sizes, like check the height of the colliding object and do a calculation that sets the player to the correct size.
or a better idea is to give the object an instance variable, and that will determine whether to grow or shrink.
if you don't want to deal with Height and Width, then just use scale.
there is no Player.scale so you have to make one manually. Just set an instance variable on the Player and everytime you effect it do:
Set Player Scale to self.scale
so a 9x9 object would have an instance variable change_amount=0.1, your 10x11 would have change_amount=-0.1 then for the opacity you'd have change_amount=self.scale * 0.1
then set Player.scale to Player.scale + Object.change_amount
then set Player Scale to self.scale