1) Whenever an individual creates anything, it's automatically "copyrighted" (whether you they choose to identify it with a "© 2013" or not). If they're an individual then they're the owner, if they're a regular employee then their employer is usually the owner, and if they're a contractor then they might have to sign it over to the employer in that contract -- all of these depending on the country.
Copyright is a right that you have by default - you've got to sign it away to get rid of it.
Same goes for trade-marks -- if you trade something using a particular mark, then it's a trademark (whether you choose identify it with a "" or not), and it's protected by trademark law. If you're an absolutely massive company that needs to remove all ambiguity about your ownership over a mark, then you can register it, which is the, quite rare, ® kind of trademark.
2) There's nothing special about games business to other business, really. Make sure your liability is limited and your books/taxes are all legit, as usual
If you want to publish your game via closed platforms, like game consoles, then you'll need to enter negotiations with those gatekeepers (Microsoft, Sony, etc) in becoming a licensed developer and buying dev-kits, in exchange for a large wad of cash. They'll likely want to see your bona-fides that prove you're capable of making the products they're accustomed to.
The usual disclaimer -- IANALTINLA.