Hm, well, there's not a fundamental page that lays out the rules of this universe(probably should make one along with a new user guide). But generally, I recommend reading more recent pages and seeing what they do with everything. We have our Guide Hub, but some of them are a bit outdated, so don't follow them to the letter.
We have a no canon policy, but many people enjoy watching each other expand on previous ideas, so that's something to keep in mind.
As for groups, I would take a look here: Groups List. Those will be a good place to start. But then go ahead and see how other people use them, and don't be afraid to ask questions :)
