Am I required to attend Annual Training in the same year as my AIT?

It will be up to your unit. Annual training and military education come from different funding sources and are not technically interchangeable, but in practice, most units recognize that it can be a hardship for employers to have their citizen soldiers conduct much more then 14-21 days of duty. Typically, you will be afforded the opportunity to attend if you want to and your leadership should ask you about it. There are many reasons to want you to go, despite already having training time. The most important reason is this will be your first opportunity to see how your role with your newly minted MOS will work within your unit's mission. I suggest, generally, that these types of questions are better off asked of your first line leader. Even on military themed social media, the best we can do is provide general educated guesses

Nope.
Your unit can make you go to AT. It is a unit training event like any other.
You will be expected to attend all of them, unless specifically excluded for some reason.

Your Company Commander can excuse you from AT for having just finished a long school in the same year, or any other reason. He can excuse you, but does not have to.
The authority to excuse a Soldier from drill or AT does not go below Company Commander level.