Any SQL server database that the tables can be created in and accessed will do. For simplicity sake you could do this on the same database as the Fiber Manager data, or the same instance but with a separate database, but if there is a server better suited to be accessed by the machine running Wavepoint then that should work equally well.
Regarding the URL to access the Wavepoint application, this depends on how your IIS server is configured but by default it will probably be something like "http://hostname.domainname.com/Wavepoint", or just as you'd guessed, localhost from the machine running Wavepoint.
You'll need to set up the user database tables in order to access Wavepoint at all, but once it is set up you can just continue to use the default "admin" account before setting other users up. Creating users is done via the administrative console inside of the wavepoint application, it should be pretty straight-forward.