I am replying for fun, since it is my original question you are seeking further information on. Please wait for confirmation from someone who knows a lot more than me.
The roth contribution and medical insurance premium deduction can do double duty because you get no immediate tax benefit from the roth contribution, so it is not a deduction against your self-employment net profit. The insurance deduction is an actual $16k deduction, so you have $4k remaining to deduct from your net profit. I believe that you can put that into a non roth 401k. Despite the roth doing double duty with the insurance premium deduction, you can't put more than your net profit for both roth and traditional 401ks combined. As for a traditional IRA, that is separate from your business and so you put the full allowable amount (7 or 8k depending on your age) into that regardless of what you put into the 401k.
I'm curious to see if someone who knows what they are talking about confirms the above.
