Having gastric bypass surgery in about a month and will require 2-3 weeks off right before a crucial training program begins (I WILL be back for the start of training). Do I have to tell my employer what surgical procedure I'm having done? Afraid they would balk at paying for my disability leave if they know it's an "elective" procedure.

The decision of whether a procedure is paid for or not is based on the specifics of your company's medical insurance plan. You can call the insurance company to ask if you're not sure. Many plans require that you or your doctor call ahead of time - prior to the surgery - to get authorization or else it may not be covered.

As for whether to tell your employer - you have no obligation to tell them any specifics if you don't want, BUT you certainly do need to tell your boss and/or HR that you will be out for medical reasons, UNLESS you're planning to take this as vacation time. They will most likely put you on a short-term disability pay plan, which after a week or so may convert over to a long-term disability play which may mean you get reduced salary for at least some portion of the time you are out.

It depends on the terms of your company's disability policies. A company is NOT required (at least in the US) to give paid time off at all. If a company does so, then they must have a set policy that defines the conditions under which paid time off is granted. If this policy requires that STD or LTD not be provided for elective procedures, then they can ask you and you have to provide the info.

You need to get a copy of the written policy on STD/LTD and read it carefully.