At this point in time you will have 2 possible disqualifications. The one I am sure of is for the osteosclerosis, the second that is possible is for hearing loss greater than the standards.
If you undergo surgery, that will be also be a disqualification, but if it does take care of the osteosclerosis and improves your hearing to within limits it could possibly help in the waiver process.
There is an item that you failed to mention in your post, the first is when are you applying to ROTC? This year? Next year?
If you are applying for this year, I highly doubt you would be able to receive a waiver even if you underwent the surgery right now. If you were applying for next year, then the chances of a waiver would be higher.
The number of disqualifications that you receive would not be the issue, the issue would be the medical conditions. So in your case, if you had the surgery, you would possibly have 3 disqualifications, but its the underlying condition that is the issue.
I'm not 100% confidant that even if you underwent the surgery that you would be able to get a waiver. I am certain that with out the surgery that it would be VERY difficult to get a waiver.
I am not here to make medical decisions for any one, or to advise anyone on what medical decisions they need to make. In your case I would sit down with your physician and go over ALL the options you have, to include the benefits and risks associated with having the surgery and not having the surgery. Have your parents there as well. Go into the meeting not looking at just ROTC, but at the rest of your life. This is something that could affect your quality of living. Make sure that your quality of living is taken care of before you look at what you want to do with that life.
If you have any other questions please feel free to let me know.