I am afraid I must disappoint you on both questions here. At least for data sources. There are no data source that can help you with this information.
As far as finding the name of the page template, there is no way you can do that at all, through the portal. I guess we just never thought any developer might need that, so the only way of getting that information is by connecting straight to the database and using direct SQL, which I would not really recommend.
To get information about the user, there is a solution: Try using the Java API in a plugin: http://repo.enonic.com/public/com/enonic/cms/cms-api/4.7.17/cms-api-4.7.17-javadoc.jar!/index.html - If you create a function library with your custom methods, these may be called from the data sources and give you access to the information needed in XSL.
The function you create, can use a
com.enonic.cms.api.client.Client, normally in the form of a
RemoteClient, which has methods for
getUsers. These will return all the information you need about the users you ask for.
Hopefully that is at least of some help for you.