Hi B.!
Age three is much harder than age two in my opinion! They tend to get mouthy and push the limits and have a sense that the whole world belongs to them (if I see it, its mine!)
It must be hard with the added "crowd" mentality that creeps in with twins, they are never the only one responsible for misbehavior if they do it together! What every you decide to do, you have to be consistant, or a three year old will spot your weekness in a milisecond.
The best advice I ever got came from a preschool special education teacher. She said to tell children what you want them to do, and avoid repeating what you do not want them to do like "stop getting out of bed." So if you want them to stay in their beds, say "get in bed" or "stay in your bed" This helps them to know what to do and to process it right away instead of having to flip around to the oposite of what you have told them, some kids can't do this yet, so they will do the last thing they heard, which is the opposite of what you want.
I have also found that I have to break things down for them, if I want them to get up in the morning, I say "put your feet on the floor" then "stand up" "walk to the bath room" instead of just "get up" because they can lay in bed and still be "up". The older they get, the more they will play with your words and keep you discussing what you told them to do instead of doing what they know you asked.
Good luck. I hope things go well for you as a special education teacher. I hope that you will look at the parents who sit across the table from you at IEP meetings as the experts they are about their own children. If you listen to them (even when they are a pain!) they will probably appreciate it and work with you too!
M.