These questions are related to versions of Wiretap servers and Wiretap Client API.
The Wiretap API is backward-compatible with new servers, so there is no need to recompile. The only time you need to update is to get new API features or bug fixes.
Each version of a Wiretap server enables/extends its feature set. When talking to a specific server, the API might need to know what functionality is available, so a Wiretap server provides vendor, product, and version information to the client.