You have a lot of questions and several are not able to be answered with an easy black/white answer. Bottom line is that you should not have to choose between regular and medical retirement since you are already retirement eligible. If you are deemed to be disabled, then a percentage of disability is determined which can range from 0-100%. That portion of your retirement pay will then be deemed to be disability pay rather than regular retirement. The remainder of your retirement will be regular retirement and taxable. If the MEB determines you to be unfit for duty, it is likely that you would be placed on TDRL where you will be paid at 50% disability until a final rating is determined. You should still receive the remainder of your retirement as well. There are some other considerations, but as a general rule, you would probably be better off under a medical retirement.
If you have more questions or if I can proide any additional information, please feel free to contact me directly at [email protected] or (757) 420-9321.