Any number of background tasks run from the scheduler can be run at a time without impacting the user counts. The only requirement is that on Windows you include the -bkg option on the command line which disables any keyboard input or screen displays (i.e they are truly background processes).
As for iNomads, the user count determines the number of Browsers that can connect concurrently. A 2 user Wayfarer license, for example, will allow two browsers to connect to the server. The browsers can themselves spawn multiple sessions as long as they run from the same browser. If the user uses two different browsers (or embedded browser controls) then they will be considered two users.
PxPlus has four types of licenses; Base, Pro, Web and Wayfarer.
With the current version of PxPlus, Base licenses include almost everything that is found in a Pro license except ODBC and WindX. iNomads is included with a Web or Wayfarer license. A Wayfarer license is a Base license with iNomads enabled that disables program editing.
For information regarding your specific licenses, please contact your reseller.