1) I would double your estimated time to build. Worst case, think it would take 9-12 months.
2) Personally, I wouldn't get too into the finances of my co-founder. I'd just want to know that what are bringing (financially, sweat equity, and/or key industry knowledge) are equal. If I'm bringing 50K, my partner should too.
But to answer your question, if I was that co-founder, I would. I would look at paying off the debt and lowering the overall amount we needed to get to MVP.
3) Numbers look more than reasonable. Actually, I know a lot of people that would never have that much to bring to their own startup.
4) Don't touch the 401(k) or Roth.
Are you sure you need all this money and time to get your MVP ready? If you're bootstrapping, why not stay at your current roles and code in the mornings, evenings, or weekends?
Get your MVP done, get it into the hands of customers, and see if you find a fit. I'm not sure you need all that time and money...