I did not see any official statement about running ARR with IIS and WAP on the same 2012 R2 server, so I just tried and it seems to work fine.
I use the IIS only for http redirect and WAP for https.
And I use the IIS for some http -> https redirects. That was another thing I missed in the WAP.
For this you only need the IIS role and "HTTP Redirect" feature. The redirected request does to the WAP and will be forwarded to the internal server.
Just installed the IIS Role and got the ARR Components from:
Manual x64 downloads at the bottom.
When creating a Server farm, you still see the https destination Port, but if you didn't create a https Binding in IIS it will not be used.
As far I did not see any problems with that.
With Powersehll "Get-Webbinding" you could see what Bindings you have in the IIS.
With "netsh http show sslcert" you see the SSL Cert Bindings (from WAP and/or IIS).
Keep in mind that WAP and IIS use the same http.sys kernelmode service.