It is really impossible to give advice on lunging without seeing the situation. Your body position has a lot to do with it. I highly recommend the Monty Roberts site for advice - you can view videos and read articles. There are varying points on lunging - one being you need to have outside contact (side rein or long line) to help with proper bend. That, and having join-up established is key.
The stamping - I guess annoyance. Is she uncomfortable with something - is she out in her spine? Is the tack uncomfortable? Does she not feel good? I usually start there. Have you ever worn uncomfortable shoes or had your back hurt and HAD to do something that provoked it? It sucks. Some people tack up like they are in a whirlwind - I like to tack up and give my horse massages, scratch the itchy places, and stretch. I learn about where my horse hurts and it does wonders for the mood. They get sore muscles just like we do. Have you ever gotten a massage? All I have to do is see my massage therapist and my mood lifts. That is the response I want my horse to have with me.
Also, maybe she is just being cranky. My 3 yr old, Vertigo, can go through these mood things, where he would rather be in the pasture than learning how to be a riding horse. I can usually capture his attention with games I know he can't resist - carrot stretches are fun. This usually changes his mood. I also just have the belief that he can have a sour attitude, that is his choice, but he still must mind his manners and do what is expected of him. If he breaks the rules, I get after him. John Lyons says to "move their feet." If he steps into my space, I back him out of it - immediately. I use my big mean voice, body language, and energy. I get the "I am sorry" response from him, he submits, then I DROP IT. I don't hold a grudge and I move on to the next thing. If he stands quietly, I tell him, "thank you, good boy." Horses are "in the moment." We need to learn that as well.
If she is cranky that is fine, but if she is disrespecting your space, get after her, and move on to greener pastures. See Clinton Anderson or John Lyons resources for these training concepts. Monty Roberts also helps. Good luck and let us know how it goes!