I've worn an "open" bra (not a corset). It felt just like a normal bra - just without the support! ;) So depending on what you're wearing the corset for; if you're pert then it shouldn't be a problem. (BTW the bra was/still is a huge it with hubby)
Are you looking for a real corset, or a lingerie corset? If you're looking for something to wear out, please, please, PLEASE don't buy a lingerie corset! It looks SO trashy! If you're looking for a real corset, then I'm sorry to say that you will not...
A bodice is more like a corset, however it doesn't have all the boning and support of a corset. Corsets are designed to thin and support your upper body, giving you that "hourglass" figure. A proper corset will make you look at least 2 sizes smaller....