Hi Sherbi5,
First thing that came into my head is "why can't you pay off your dad early?" You can calculate the total lump sum for payoff including the 3% interest and clear that off your plate. Your dad would probably like to have the money back sooner as well. Why draw it out over 10 years when you could probably crush it pretty fast.
So a couple things you may look into given your income level:
*Your taxes will be high, so any opportunity to shelter cash tax efficiently (18.5K in a 401k, anyone) is a good thing to consider. Even if they have the worst investment options in the world, all the better that you're leaving in a year and can take it with you.
*Best case scenario your new job will have a good 401k and you can roll over your previous 401ks (and potentially any tIRA money - reasons why below) directly. Rolling over is easy, I've done it with mine, most annoying part as with all investment firms is the snail mailing in signed forms and waiting.
* You're relatively high income, without the offset of being married to someone who makes significantly different $$ than you.
1) You may hit income limits that eliminate your ability to contribute directly to a Roth IRA, and may need to consider a backdoor roth conversion. Super easy, just look it up. It does require that you DO NOT HAVE ANY TIRA funds to be the most tax efficient though, so rolling old 401ks over prematurely into a tIRA may make you have to take some extra steps. My partner did that, but found out he was able to roll his tIRA into his employer 401k, opening him back up for tax free backdoor roths.
2) google the "Marriage Penalty".
Your Specific Questions:
Would you max out the John Hancock 401k? Yes
Should I start a Traditional IRA in addition to the Roth IRA I have? You can't deduct anything on a tIRA if you technically have access to a employer 401k, so no. Look up backdoor roth as needed to keep doing that EVERY YEAR.
Should I continue investing heavily in the Index funds before adding to my 401k? Tax advantaged accounts first. 401k and roth every year, any additional $ can be invested in taxable accounts after.
Am I missing something? Maybe, if 401k expenses are wild, then the advice above does not necessarily hold. See what you can find out in advance regarding the offerings at the job you hope to have next year. For this year, a single year of shitty fees & expense ratios will not change the advice, you're certainly better off shielding 18.5k from the tax man NOW. For the next job, you're probably better off in the long run shielding the money from the tax man, the question is - how long do you want to keep it in an account with bad investment options or high service fees and expense ratios (you can sometimes roll out of a 401k without having to terminate employment)...but then you balance that with your ability to continue doing a backdoor roth if it has to go into a tIRA.