Well first of all OSMC installs a standard Kodi which allows you to install what ever Skin you like best. But yes the default (beautiful) OSMC skin also shows recently added movies and TV Shows!
I am not aware of a Genres tag in Kodi!
As it has been said here on the forums several times 100Mbit should be sufficient for 99% of all available content to watch at. If you are unsure check with mediainfo some of your files for average bitrate.
SMB is ok to use while NFS would be more performant. If your NAS also provides NFS capability would recommend to use that. When using SMB you might have to check if fstab based mounts are more performant for you. You might want to read up this thread
Correct, during first boot up the setup and configuration will be finished but other than that no preparation needed.