First of all, I would like to thank you very much for the informative and prepared answers.
To your question:
Yes, I use the Zorin client as a multiple user system, with the purpose of having a system administrator (Supervisor) and two normal users (Beatrice and Urs) with standard rights.
For the automated start of the scripts after the login process, I placed the three users in the IgnorePassword file to suppress the password query as follows:
To my first question 1. Connect Zorin client to local network via SMB protocol:
Basically, I always want to use a computer system with its on-board resources if possible. I can basically live with the workaround described for integrating the SMB shares in this topic.
However, my Synology NAS DS214+ supports the NFS protocol in addition to the SMB protocol.
At the moment I am still experimenting with the Zorin client connection via the NFS protocol and will decide on a specific transfer protocol depending on the tests carried out.
Regarding my question 2. Network browsing, I found the following statement in the gnome forum.
Thanks to your recommendation, I will be happy to consult the gnome forum regarding the development status of GVfs.
I have just activated Zorin's internal firewall, although I am aware that my local network is behind a router with an integrated hardware firewall.
Regarding antivirus protection, I have the same opinion as your statement. 
With that in mind, it was an honor to talk to you about using Zorin OS and I thank you very much.
Best regards,
Kobi