1) This is a supported configuration. THey say not to install Sense and NPrinting on the same box. YOu can install the designer on your own machine if you want. You can add more engines across other servers but there is additonal cost to that.
2) Both you schedule tasks user and publishing and create your reports from there, when you ad a new report you edit the template to open your designer up.
3) Go to Admin>Engines to check status
4) The username you need to give is a user probably a domain one with access to your Qlik View Dashboard you want to connect to this is not a section access request.
5) Yes this seems ok. You can setup non windows users to access your reporting in the import task.
As per your suggested link - AllQlik NPrinting components can be installed on the same machine. It is also possible to install Qlik NPrinting Server, Qlik NPrinting Engine and Qlik NPrinting Designer on different machines
Also, I checked the same notes during installation of Nprinting components to the same computer.
Yes you can install all Qlik NPrinting components on the same machine or each on a different one or any combination - all those scenarios are supported. Installing NPrinting on the same machine as Qlik SenseEnterprise or QlikView Server (as your point 1 suggests you have done) may work but is not supported.