As far as "minimum" or "normal" retirement age you'll have to ask the military what that is. Generally, it's the earliest age at which you could have received a pension without being disabled. I believe it's only asked on 1099-Rs coded as due to disability, but I may be wrong.
That question has multiple purposes: First, I believe military disability pensions are exempt from income tax (though I'm not 100% sure). Even if they're not, if you are under that age TurboTax is required to report the pension as wages, which denies any "basis exclusion" (a pro-rata portion of each check representing your after-tax contributions to the plan if any, which is not taxable) but also makes the pension "earned income" for EITC purposes.