How do I establish dominance with a foal?

I trained a stubborn colt a few years ago. To answer your first question, halter break as soon as possible and start leading them around every day. Repitition is key whenever training an animal. For the second question, get a squirt bottle and set it to a single stream not a mist. Every time they nip kick or misbehave, give em a good squirt of water right between the eyes or on the soft part of the mouth. Doesn't hurt at all just very annoying. They'll stop.