I would agree and encourage with almost everything here - the only adjustment I might suggest is that:
a) If you didn't even know IIS was enabled on the server
b) You have no apparent need of IIS on the server
Then rather than reconfigure Clarity's port so they can both live in harmony, just shut off IIS - this will leave your system more secure (because the above would likely imply you have default credentials and setup for IIS which can be a vulnerable position), as well as free up some resources for the Clarity services that are being wasted.
If administrating the server isn't your (the OP's) role though, then before making a decision either way, check with the person who is the administrator and see if IIS is needed and desired on this machine.
Usually with our customer base, the experience I have is that IIS was not wanted or even 'known' when conflicts arise with it, but I acknowledge that won't be the case every time.