1. IMHO, worth it, especially if one user can log in from different computers (roaming profiles are good too). Passwords are mandatory, and at least versioning (history of edits) in the documents.
2. If no immediate plans of implementing a document management system and roaming profiles don't want the network folder(s), IMHO, always under the company documents (personal files can be stored locally) with a regular bacopa and a tested recovery procedure of the server in case of failure of the screw/motherboard. You can try to use synchronization of folders and files, if users will complain about slow speeds on the network.
3. In principle, implement an antivirus scan (e.g., registration/lock) all traffic and network files only through the server is possible, but the probability of infection of workstations will be higher than if the antivirus was working locally stick, Packed viruses, etc. the server I can not check.
4. Read the Law No. 152-FZ I think is a very big trick to small business in General, and to mini-hotels are very-very big, because personal information under other laws/regulations they are required to collect and process (to be supplied by other operators) and not where it is done manually on paper.