While I love Kevin Corrigan (that's my vote from your list Sean),
I think we're all forgetting a very valid option.

Notice that the post says they are *casting* for the role of Corwin. So who better than the man himself? I'd say he fits all the criteria. Please note the following pictures and consider this option. =]



Move to LA, Cor. Be a star.
I do have one backup in case you don't have the acting chops to make it:

Jermaine from Flight of the Conchords