Depends on the rabbit, some are more vocal than others.
Right, running back and forth is more a sign of exitement and expectation than aggression, fear or whatever. You should see my buck when the girls parade in front of his hutch...
Grunting, in combination with starting toward your hand and pawing it is a different thing, I wouldn't call it aggression, but making a point, like "Too, close! My space! Back off!". Can be quite scary, but imho is still a quite civilised way to get the point across.
Anyway, just stay calm, spend time with him, if he lets you pet him give him nose rubs, scratch the base of his ears, if not hold a treat and start while he's concentrating on that, it takes time but it's so much fun to get them around.
