Well to find out if it's the water pump you'll need to check for leakage from it right off the bat, otherwise remove it and have a look at the fins' condition (worn down/broken/gone), any of which would suggest that the water pump has released bits of plastic into the cooling channels which can get lodged in certain spots and cause the coolant not to flow properly and overheating portions of the engine block (obviously not good). Also spin the impeller and if it sounds like it's grinding and doesn't move smoothly, replace the pump.
Put it this way, as I was told: if you or the previous owner have never replaced the water pump, do it. And then do it every 3-5 years from then on as preventative maintenance, because at some point the plastic impeller
will fail.
As for the oil, unless you just did an oil change very recently then there won't be any harm in potentially getting rid of your oil for a fresh chaneg, so go ahead and drop the pan and get a look in there, and take a good look at the filter element...if you can see there's a bunch of fine, shiny metal shavings in the pan or filter and/or large pieces of clear, plastic-looking pieces in the pan, these point to IMS failure.
If you haven't already, have a look at LN Engineering's site, good read and info:
Intermediate Shaft IMS Upgrade and Retrofit Kit for Porsche 911, Boxster, and Cayman models