LAN only: Yes, ownCloud with Collabora Online will work on a LAN only, the ownCloud and Collabora Online setup must be on the same LAN as your web browser. A couple of features such as translation do require the Internet.
Features of spreadsheets: Yes, real time collaboration will continue to work with other users on your LAN. I am not sure what you mean by access control over columns, but it will work the same as if the ownCloud and Collabora Online setup was accessed over the Internet.
Type of configuration: A Virtual Machine provides better performance than docker, but docker still works well.