Not coincidentally, since we were both in the area, I went to the same school as Jason's wife Amanda. For the same reasons Jason mentioned, I wouldn't go to culinary school if you mostly want to decorate cakes. It was VERY EXPENSIVE and although I had only been doing cakes as a hobby for about 3 years before going to school, when we got to the decorated cakes unit, I actually was told by my chef instructor that my support system (SPS) was better than what they were teaching. My sugar flowers were also a lot more intricate than what they were teaching.
I now own a cake and pastry business and do a lot more than just cakes, but I still think school was way over priced and I should have gone to a community college program where they paid attention to the business side of things as much as the baking. If you do take baking classes, try to make sure you learn how all the ingredients interact. They didn't teach much of that at PCI. Also, we always did everything in small batches. When you go commercial, you need to know that everything takes longer in bigger batches, and how to be efficient. I went without doing the research, because it was there and I could do it without much effort. I'm not unhappy I went, but it was not all that helpful.
If you just really want to learn to decorate, seek out classes for cake decorators. Take a look at Cake Camp if you want to study decorating. http://www.cacakeclub.org/. A lot of big names teach there. (I took class from Colette Peters, NIcholas Lodge, and Debbie Brown one year) . Nicholas Lodge also has classes in Georgia http://www.nicholaslodge.com/ and I did a week with Laurie Ann Blethen in New Jersey. Also, there is http://www.caljavaonline.com/classes1.htm. I did a class with Ron Ben Israel there. All of these seem expensive until you compare them to $25,000.00 - $30,000.00 or more for culinary school.
I left a research career and went to The French Pastry School in Chicago. That was over 10 years ago. Then, the tuition for the 6 month (very intensive) class was over $15,000. Now I'm a stay at home mom decorating cakes on the side. Was it worth it? Hard to say. I learned a LOT, but the job market is crazy with a ton of people trying to become the next celebrity chef and working for very low pay. Since you already have a handle on cake decorating, I would take more classes through Wilton or at craftsy.com (AWESOME classes here!). Then maybe take a community college or online class to learn more about the business side of things. Hope this helps!
Community colleges offer business and baking courses on a continuing ed basis--meaning that you take as many or a few as you really need, if you don't care about a diploma. Much less expensive, do them at your own speed, you should be able to ask questions about the exact material taught before you sign up.
Take this offer if it is still available.
A bakery or deli or sandwich shop is the ideal place to learn how in practical terms (as opposed to in theory) to keep your profit margin in the black. No they don't teach that in business school or culinary school, you learn it in internships or in paid work.
As far as your other questions about cake technique, give us a list of the specific ones you want to learn. There are excellent books out there that are discounted at Amazon--and then you just practise practise practise using cake tins and supplies like icing over and over.