1) when 72t is applied, is it applied to one account, all tax deferred accounts or something else? YOUR CHOICE
Meaning my Rollover and Roth are with T Rowe Price, if I roll the 401k over to Fidelity or Vanguard, is the 72t calculation supposed to include balances from both custodians? 72T is a plan that needs to meet IRS Guidelines. Much simpler if 72T funds are all in one place in my opinion.
2) when 72t is applied, would it make sense to raid the smaller balances (wife's accounts) and leave the larger balances intact? The amount of money needed the first few years is minimal because I think one of us (me) will retire before the other spouse. Would after tax savings cover the need if short term? If not, set up a 72T against whatever amount and account you need to.
3) as opposed to using (relying on/ planning) for 72t, would it make more sense to stash away money in a taxable account and let all money grow tax deferred or tax free? Each account is invested with a very similar allocation (45% large cap, 15% mid cap, 15% small cap, 25% international or 15% foreign large cap and 10% foreign small cap or 15% foreign established markets and 10% emerging markets). After tax accounts are great once the match from employer in the 401K and IRA's are funded 1st in my opinion.
4) 18 years from now I am age 53 and wife is 52. 72t is designed to last 5 years (58 yo) or until age 59.5 (6 years) whichever is greater- so 72t is a 6 year withdraw, correct? Correct on you but 7&1/2 years on wife till 59&1/2.
5) Part of the ER period will be used to convert monies to a Roth if possible- if that affects the 72t withdraw, can someone please comment how? For example if Rollover IRA is 300k and we need 50k taken each year for 72t, could I withdraw 50k, convert 10k to Roth, then next year withdraw 50k and convert 10k to Roth... might run out of money in year 5 or year 6 to satisfy 72t rules... what are the consequences of this? (obviously I could raid another account for the income, but the original 72t provision might not be met). Once the 72T is started you can still make conversions on the accoount but AFAIK you need to designate a ROTH as part of the plan for the 72T.
I suggest reading a lot at Welcome to 72t on the Net
to get your arms around the 800# gorilla of 72T.