Don't know about upgrading a Priceline room. They let you do it on free award nights, so you'd think they would, but Starwood seems to be doing everything possible to make Priceline-booked rooms as unattractive as possible (except, of course, selling the rooms through that channel), so it wouldn't surprise me if you can't do it.
Here's
a link to the award chart for Starpoint upgrades. Break out your de-coder ring, though. You'll need it.
