I noticed when i view my stats there is a count for how many enemies i have disarmed. How do you disarm someone?

My other question - Is there a way to get my horse to STAY in my stable that I've built for him/her? I put the horse in there but if i try an fast travel it seems to appear with me regardless.

You can disarm with the disarming shout or disarming bash skill from the blocking tree.

Since one's "LastRiddenHorse" always travels with one, using a conjurable horse should cause no horse to follow in fast travel, once the spell duration expires.