You are definitely doing the right thing to decide to try again. Just so you know, over-abundant milk supply also hinders breastfeeding due to latching problems and over-feeding (he developed GERD and had to be handled carefully after nursing).
I think you hit the nail on the head with the pumping. Start a day or two after delivery in the hospital's pumping room or in-room with a hospital-grade pump. Arrange for a hospital-grade pump rental. Get a prescription ahead of time and look for a long-term rental. I was blessed to find one for about $20/month. I got a little crazy about the formula in the hospital, sort of boycotted it and pumped every 2 to 3 hours to generate a good supply - remember when they are newborn, their tummy is so tiny (the size of their first).
Get some books by Le Leche League and read them, especially the parts about galactagogues such as alfalfa, Aniseed, Blessed Thistle, Fennel, Fenugreek, and even beer. Drink water copiously while pumping and nursing. Go to Le Leche League meetings with your baby and nurse with the other mothers. You would be surprised how fast you start producing when you see all those other mommies and babies nursing.
Set a goal in sight (I will nurse for at least 6 months, etc); find a consultant who can help work through latching problems (we worked really hard for the first 5 weeks). Personal stories: my son and I had latching probs and I felt a failure. Then one day he "got it" (it helped that my consultant had me start pumping a little before we nursed). My son self-weaned at 4 years of age. I was just too easy after we got through the hard stuff. My sister in law observed how hard-core I was and researched breastmilk. When my nephew was born, his mouth was so little, they said he wouldn't get a good latch (he couldn't get his mouth open wide enough to get the areola). So, she pumped with that hospital grade pump for ONE YEAR! To make sure he had breast milk.
I like the Mother's Milk Tea, although I didn't need it much (tastes good though). Also, do not pump until after the baby is born unless he/she is full term and it would be ok to induce labor. Pumping will stimulate the uterus to contract. Also, to answer your first question re hormones, pumping stimulates oxytocin; http://en.wikipedia.org/wiki/Oxytocin.
Blessing to you - it will all be great in the end!