401(k)s and IRAs are handled separately in this calculation, even though each has a required withdrawal.

You would have to check the rules of your 401(k) concerning distributions to see if you can use these funds to purchase an annuity. If you qualify for a rollover into an IRA (that happens to be an annuity) then [continue]

The RMD of your IRAs is ultimately calculated based on the total value of all your IRAs. You would use IRS charts to figure out what the RMD is. You can then opt to take that amount out of one IRA, or some out of each of your IRAs (though the trustees often make it sound like they expect you to take the RMD out of each account, it isn't required). So, if some of your IRA is locked into an annuity that you can't touch, make sure you have another IRA that's liquid enough to pull the RMD from.

Yes the RMD's would be based on the existing balance but you would be taxed on any amount taken out of a 401k that was put into a regular annuity. You might want to make sure of what you are doing as you may hurt yourself pulling alot of money out of a qualified account and putting it into a non-qualified account. You dont want to pay taxes on say $1,000,000 in one year. That could really hurt you.