On the plus side: Noting that both additive and subtractive processes need the same kind of x/y/z positioning platform is a good insight.
On the minus side: I'm not at all convinced I want the swarf from milling contaminating the printing process.
1) I think the shop vac is only intended as a swarf collector for the milling process.
2) Coolant pump/mist collector? I don't think I've seen those in other small 3D printers (RepRap and the like), and I know neither is an issue in small wood/plastic milling systems. They would be an issue if you were using a cutting fluid and milling metal, but that's explicitly out of scope for this machine.