This doesn't sound like the mare has un-balanced hormones in my opinion. Mare magic/red raspberry leaves is for estrogen dominance and balancing hormones. Assuming a supplement will take care of a whole lot of behavioral issues is a far leap ;) Typically estrogen dominant mares will be moody, grumpy, lazy, cinchy, reluctant to work, sometimes act colicy from cramps, be dominant in the pasture, hard to or un-able to get in foal...
Without seeing her and going only on your description I would chalk a great deal of this up to the mare needing a trainer or a confident handler to have a good smack down with her. It isn't at all uncommon to hear of someone who took in a under the weather horse & loved the horse only to find that a few months down the road the horse was a lot different when his/her health was back up to par. I have ended up with more Thoroughbreds than I can count because of this ;) There are a lot of people who keep a Thoroughbred thin because they are easier to handle. I do not agree that this is right, but I personally know of many.
It sounds mostly training related to me but looking into deficiency possibilities to help the training process is always a great idea.
You can take a look at my website, or google things for yourself, to see if anything fits the bill. Natural horse - New Image Training Center
Right off the top of my head I'd say:
Magnesium deficiency can make a horse hot, nervous, flighty, un-able to handle stress etc...
Calcium deficiency can
make the nerve endings raw and can
give you a "crazy" horse.
Valerian root is commonly used to decrease nervous conditions in horses, it is a mild calmative and anti-spasmatic.
Vervain flower essence helps animals always wanting to be involved, high strung & with fixed ideas that they are right.
Deficiencies can cause major side effects and coming from any rescue situation you are almost guaranteed a deficiency or an emotional train wreck. Supplements, herbs and oils will help this but if there is an under lineing training problem they will not train the horse for you :)