1. I'm assuming that before you showed it to anyone professionally, you yourself cut it to ribbons and glued it back together a couple of times during the drafting process. Each time, it should have got stronger and more like what you want to say. Either that, or you're doing some kind of Kerouackian "first thought, best thought" method, and you've got the chops to back it up. If neither of these things is the case, go back and edit again: most authors I've talked to do 2-3 drafts, plus one last run through for polish.
2. Once you've got your self-edited manuscript, you get yourself the best agent you can find. Currently, this is where most manuscripts reah a bottleneck, as there are far fewer agents than publishers right now. Your agent will be your advocate both during and after the sales process, and can specifically negotiate "final approval" into your contract, if you're really touchy, or have been burned before.
3. Once your manscript has found a home at a reputable publishing house, the liklihood that they're going to perform radical brain surgery is quite low, for a couple of reasons. a) They picked your book out of 1000+ others, and paid good money for it, so they probably like it, b) the staff editors have something like 20 books each to put out in a given year, which means that you're more likely to get too little editing than too much. They mostly don't have time. If they do do somthing you really don't like, you can a) tell them, b) if that doesn't work, request a different editor (very rare), or c) try to buy the manuscript back. I've heard of exactly two cases where it's gone this far (one in the 70's and one in the early 80's), so you have very little to worry about.
4. If you go over into other genres/media, such as film scripts or magazine articles, your work will get the heavy edit, almost without exception.