Hi @HellenicSpring, Welcome back! I have asked the community team about adding more badges, specifically bringing back the Age of Empires Insider badge, to the new forums. Hopefully it and more badges make a debut before the next DE closed beta starts, which has yet to be announced.
The change over to match our gamertag was implemented because of a login bug. More info here: Forums Username Changes
The Latest and Unread filters are probably my favorite features because it helps you stay updated on the latest forum activity across all categories. The previous forums filtered topics by Last Updated, which only showed you topics with the most recent comments and buried new topics without any replies.
Endless topic scrolling is probably my least favorite feature because it takes longer to find a specific post in a topic with a lot of replies. It is a lot easier to remember the page number for a comment than the comment number. EDIT: It appears you can bookmark individual comments for easy access later and use keyboard shortcuts to navigate a topic one post at a time.
If you have any other questions about the new forums, feel free to ask.