WCF handles most compatibility problems without complaints, such as adding new parameters to the method (old clients are still working, new parameters are initialized by default). Deleting parameters also does not affect the client (additional parameters are ignored). Other changes and solutions can be found here: http://msdn.microsoft.com/en-us/library/ff384251.aspx .
To deploy, as indicated in another answer, click once - this is a quick way to automatically update client machines, if you prefer a larger push model, you can configure msdeploy to push the assembly to another machine (if you have access to them).
Hope this helps.
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