Start the waiver process now. It is multi-staged, and takes several months if everything goes smoothly. You'll need a no-objection letter from the embassy of your home country. This is usually the most tricky part. Once the US Department of State gets this, you can track your status online. Start now so you are done with it by the time you finish your postdoc.
Re the O1, read up on the requirements, and work on publishing more during your postdoc.
J1 waiver isn't too bad. Yes, it involves some paper-work, but nothing that would need an immigration lawyer. You can do everything yourself, and costs about $200 last I checked.
Also look into the O1 visa that doesn't require a waiver, and has no quotas.
Vanguard Target funds are nothing but a collection of passively managed index funds. The ER is slightly higher than doing it a la carte, but it re-balances without having to worry about it.