Search for " prefill service" . This was introduced in 6.2 and is meant to pre-populate form fields based on user login. I think have posted a sample of this on the forum. If not I will post it on monday
Yes, you can use the new feature introduced in AEM Forms 6.2 called Prefill service. It requires you to deploy a OSGI bundle and the bundle will return you an xml containing the logged in user's information