Requirement in the collection considered in a baseline?

 When you take a baseline of a component, that always includes everything in the component.

This question doesn't quite make sense as written.   You can move a requirement from one folder to another, you can add a requirement to a collection, and you can remove a requirement from a collection.   But I don't know what you mean by "move a requirement to a collection".   Also, an artifact (such as a collection) resides in a stream.   You can merge it from one stream to another (once you activate configuration management), or you can delete it from the stream, but you cannot "move it from the stream".