The statement indicates that 5 different apps can observe a device with no overhead. That said multiple applications can register CTIPorts and RP but they have use the same capabilities in register request.

Dynamic registration type should be used. Static registration allows only 1 registration request. 
 
Any application can put the call on hold, redirect etc. The expectation is applications are aware of other applications and have some mechanism to co-ordinate. More practical scenario is 1 application is actively controlling (ie doing features) and all other instances or other apps are just observing the address/terminal and getting the call activity.