I intentionally left out authentication concerns because they vary wildly and even when you see the schema in RIA it is really using services to interact with the server side, so it is an implementation detail and not an intrinsic part of what I would consider
the Silverlight clientside framework (RIA can do it because it addresses both the server and client side).
As for boot strap parameters, this is what I typically do - and again, because parameters vary wildly, I like to leave that as an implementation detail instead of embedding it in the framework:
1. Create IConfiguration interface that defines parameters (ParameterA, ParameterB, etc)
2. Create Configuration implementation for this and [Export(typeof(IConfiguration))]
3. Create ConfigurationService : IApplicationService. This will be set in the App.xaml similar to the Jounce ApplicationService. In the Start method, you would call CompositionInitializer.SatisfyImports(this) and also [Import]IConfiguration. From there,
you can parse out the init parameter values (this is passed in as a context to the IApplicationService method) and load them to the Configuration, doing any data parsing/shaping needed (casting to integer, Uri, etc)
4. Anywhere you need to reference the parameters, now you can simply import IConfiguration and reference the field as needed.
Hope that helps!