1) Sure. It won't hurt anything.
2) You've got the owner's manual, I don't. Just use whatever weight it recommends for whatever temperature you're going to be riding in. It will vary person by person.
Brand of oil doesn't matter as much as making sure there's always clean enough oil in the engine.
edit:// just don't put car oil in there since it's got a wet clutch. Honestly I just use Mobil 1 motorcycle oil since they sell it at every Wal*Mart if I need any when I'm on the road. I don't get too fancy with Motul, Repsol, or whatever fancy flavors are offered at the bike shops.