Re: Which song is a better choice for Pirates of P audition?
I think either of the songs you mentioned would show off the right part of your voice for this show, although I'd be inclined to pick "Art is Calling for Me" out of those two as it's closer to the G&S operetta style. That said, it's a pretty well-known piece for sopranos to use (at least it is in my area, not sure about yours, obviously!) and if picking something that's not overdone is a priority for you, then I'd use "The Finer Things".
But if you do have time to learn a G&S number, then I'd go for that option
"The hours creep on apace" from HMS Pinafore
is a favourite of mine ... I'll let you know if I think of anything else!