Wail v. Fumarole

[Skullguy725]

The cards in question are:
{wandering fumarole}
{warping wail}
If I target the fumarole with warping wail's first ability, can my opponent switch it's P/T to make it an illegal target?
Do I have to declare, as the user of {warping wail}, whether I'm looking for 1 power or 1 toughness, or can wail check for either?

Thanks

[Skullguy725]

Ah thanks. +1