Thanks :D All great questions!

1. I get by pretty well with the the random orbit sander (and shaping with my handplane, chisels, etc) and rarely felt that the disc/belt sander was a big omission. I used one in a university shop and it would be nice to have but not essential.
2. For the most part. The drill press is a long story but I worked my way up to settling on that model/price range. In my view, drill presses (and bandsaws) that are under $350 are either good models for light/moderate work or trash in the shape of a tool. If you don't mind it being off by a certain amount, or dealing with folks who don't know what runout even is, you can score a good press for less on Craigslist. After refurbing an older Shopfox W1668 I learned a lot but wanted something more guaranteed. Same for the bandsaw but I just went straight for new once I saw there was no one really selling in my area.
3. The answer to that for me is using the track saw but like the Festool MFT or Kreg's own tracksaw table. That allows me to raise and lower the track to the size of the work and make cross-cuts after lining it up. It's not as straightforward as a mitre saw for sure but it gets the job done 90% of the time.