In order to retrieve list items from a SharePoint list through Web Services, you should use the lists.asmx web service by establishing a web reference in Visual Studio. The lists.asmx exposes the GetListItems method, which will allow the return of the full content of the list in an XML node. It will take parameters like the GUID of the name of the list you are querying against, the GUID of the view you are going to query, etc.
Side Question: I got asked how I built queries with the lists.asmx web service. In order to build queries with this service, one of the parameters that the GetListItems method exposes is the option to build a CAML query. There are other ways to do this as well, but that was how I answered it.