Now yer gettin it :). If you will save enough in taxable to get you through the first 5 years of Roth conversions, it is also probably better to do traditional IRA's. Apart from having lower expected taxes overall, IRA's reduce your AGI, which may increase your saver's credit. If you have the money available you can max out IRA's (or Roth IRA's) for both 2016 and 2017 right now, making each of those accounts eligible for admiral shares.
You ask lots of questions about stocks / bonds / asset allocation etc. but the reality is it does not matter that much at this stage. As Scandium says, any bond allocation from 0%-40% will probably be OK right now, change that to 10%-40% by the time you retire. I would not use a target date fund if I was planning to rebalance, as it would be more complicated. Personally I would probably invest in just the stock funds until they qualified for admiral shares in each account, and then start working on the bonds. Stocks have higher expected returns. Bonds are more tax efficient in IRA's, but also not especially useful except for a small amount for rebalancing. I tend to view bonds as more of a deep emergency fund, and might suggest investing in bonds or tax exempt bonds in a taxable account for that part of the allocation. Having your bonds in taxable also allows you to spend them first when you FIRE, which may reduce the risk of a bad sequence of returns as well.