Developing CRM solutions that are environment independent is not trivial. By just adding a webservice you are making your code dependant on the CRM customization of that system. If you move the solution/dll:s to another system you will be running a risk of your code not working. This is especially problematic for ISVs since they never know what system their product will be installed on. However, there is a good way to handle it. The best way is to first use a plain out-of-the-box CRM system and use the program
This will create a file called myCRMProxyClass.cs is c:\temp.
Add this to your project. This is in essence the same this as adding a web reference and adding "using CRMSDK" or whatever you named it. Hence you can access all the CRM webservice classes.
Then create the service-instance and set the url by using the registry-key added during the installation of Microsoft CRM. Have a look here if you want to know how. http://ronaldlemmen.blogspot.com/2007/08/creating-environment-independent.html
If you have other environment specific data, it should be placed in the web.config / appsettings (if using a normal web-site/virtual directory) or you can use the AssemblySettings.dll (has to be downloaded, not from Microsoft) to create a assembly specific config-file, alternatively, add you own keys to the registry.
I hope I have given you a few hints on how this is done. Happy coding!