Hi,
It looks like the "Client/Server Version Compatibility" section of the "Desktop Clients - Overview" Help topic answers your first and third questions:
As a general rule, older clients will work with a newer version of the server, but clients will not work with servers that are older than the client. However, it is always recommend to use the same client version as the server if at all possible.
As for the latest Collaborator Client installation package, it is shipped separately from the server installation package. You can download all the latest installation packages from our website.