Hi Articrose! Welcome to the forum; always sorry for the circumstances, though. Thanks for the plug, Karen. I do recommend that you read my recent posts as well as that of others, e.g. Tumbleweed. It will help give you a perspective on the actual CK prep and treatment.
As for your questions, I am happy to lend my single viewpoint, based upon my research, but I am no physician:
1. This issue is independent of whether pre- or post-treatment. My understanding is that as your vestibular nerve is severed/damaged, the other side will compensate. Sometimes this can be a smooth transition; sometimes it is not and sometimes (though, perhaps, rarely) it is chronic before or after treatment. It appears to be an issue of whether your "bad" vestibular nerve has short-circuited and is sending improper info. to the brain; until it fails completely and the other side takes over, you might have balance issues;
2. Stanford quoted me that the risk of cancer was 1 in 10,000 after CK because it was pretty theoretical. However, I was informed just before my CK treatment, by my oncologist that the patient of another physician, about a month prior, was discovered with cancer, even though very few, if any, ever had been before. She told me that this potentially affects those statistics, though no one at this point really knows how much (I did the treatment the next day; I could have backed out.) Given the sheer number of patients that have undergone GK (since about 1980) and CK (since 1994) to date, those odds still look pretty great to me; and
3. My treatment ended on this past Friday, January 20, 2012. I have no burns. The machine is self-correcting within 1 mm and the staff monitors any movement from the constant x-rays through the table to stop the machine at any moment and correct. Seems pretty accurate to me. Again, take a look at my posts and that of others to get a feel for the entire CK process from soup to nuts.
Hope that helps a little, at least.
Best of luck with your research and decision. Keep us posted.