No, you’re not missing out on anything. You can have multiple accounts if you wish, you can have one. Short of an instance going down that you have your account on, you can interact with it all.
Official as in a centralized server with all the “main” stuff? No. Each server might have its own News community.
There isn’t yet, but with the way Lemmy mods are going, it won’t be long. Starting to get some whiffs of mods banning people because they’ve voted wrongly on posts. Lemmy is unique in that it lets mods see what you’ve up/down voted.
Use the ability to block entire instances, communities, or users as much as you want here. There’s not some low-number limit like there was on Reddit. You’ll stay much more sane that way. Like if you don’t want your whole front page filled with furry porn daily, blocking lemmynsfw is a good option, without nuking all nsfw content, etc.