How to test SharePoint 2010 Web Services

Here answers to my question 1. and 2.:

1. In Sharepoint Designer you open the site over: File -> Open Site -> In text field "Site name:" type URL of your site. Than drag & drop clientaccesspolicy.xml in root of your site.
2. If you have Form Authentication, you don't need for this step create new zone (but for some reasons it can be useful). You simply open web browser and type URL of your site. Then fill up text fields (always with user that have administrator privileges) and check "Sign me in automatically". After that will Sharepoint designer use this credentials for specified URL.

If you can help me with question Nr. 3, or you have some other solution, how can I access clientaccesspolicy.xml from Silverlight, post it!

Duuude... I've had enough issues like this with various pieces of SharePoint to be thoroughly convinced that it's really still a beta product.

At long last, I've discovered that using SPContext instead of SPControl to get the current web gives me what I need. All the MSDN documentation says to get the Web like this:

SPControl.GetContextWeb(this.Context);

And, if you disassemble the built-in web services, you'll find that this is also how the built-in web services get the current web. For my service, it didn't work, and this does:

SPContext.Current.Site.OpenWeb();

Why???? Why, Microsoft, why???!!!!