Yes it's fine, but remember that when you're pregnant baby pulls a lot of calcium from you and mainly your teeth are effected, so with the whitening toothpaste you might feel some extra sensitivity since it's stripping the layers of stains off your teeth. If you have pain though, which you probably won't, just switch toothpaste.
Don't see why not. Just like with any other kinda of toothpaste, don't swallow it lol