Have you spoken to your director about any of this?  He/ she may be the first resource you should try.

Really, PinkScarf, I think B-M-D has the right of it.  Your director is the first person to go to because he/she is the one that chose you for the role, and there's obviously something about you that makes him/her see Annie Sullivan in you.

I've seen a half dozen different productions of "Miracle Worker" and I've seen a half dozen substantially different Annie Sullivans.  You need to make sure that you and your director are on the same page - not go off on some sort of "unauthorized" tangent.

I will say that you're going to have to develop a good working relationship with the girl playing Helen.  The two of you will be a team, and one's success in her role will be strongly reflected in the other's performance.

Second opinion.  You're not going to be able to fake the physical stuff.  It's going to have to be pretty real, or the audience will see that you're holding back and you'll lose them.

And the only thing I have to say about crying, I've already said before elsewhere.  Don't force it.  Forced crying always, always, always looks fake.  It's much more effective to be seen trying not to cry, than to actually cry.