Yes, it is possible for business to choose the modules that they need. See the right hand side of column and calculate. 

As both employees and managers have access to Quadim - a user is defined as those connected to the platform. The company decides who has admin access. 

Yes, modules not needed nor desired can be turned off. 

A public marketing network is a what the name entails - the ability to either showcase your competencies to the external world or  building a following around your company to communicate with.