First, I'd generally drop any and all expectations when it comes to styling in XF2 compared to XF1. In many cases, you might expect to see a certain template (like header, navigation or footer) and find they just don't exist because they're part of a bigger template or similar.
Second, when it comes to adding a navigation tab, you don't need to edit templates at all. Use the new navigation system in Admin > Setup > Public navigation.