1. Do you have to register your game before beginning the game, or can you just play a game and when it is finished, decide to input the results into Metaverse?
You start the game through the Metaverse option on the title screen. It will then ask you to login and create a character if you don't already have one. Then play your gameas normal and you will be asked at the conclusion if you want to submit it to the Meta.
2. To have a score listed in Metaverse, does tha game have to at some minimum difficulty level? I'm playing at normal, is that good enough?
No requirements. In fact it will show in your profile what difficulty you used with each game.
3. Silly question, maybe, but do you gain any points for playing a game that you do not win?
Yes, unless you absolutely do nothing and retire right away. It won't be many points but you will get some usually for a defeat.
4. I will not be showing up in the lists of top scorers, but if I can submit a game that I've won, will that add a symbol to my nickname here on the forum?
Once you have a character made you can go into your account and set that character as the default and it will display any medals you've earned with your posts.