I decided to move to FreeCAD from Autodesk Inventor as I figured it would be easier and more beneficial to make the switch earlier in my engineering career, and I really like the experience so far - lots of good documentation and tutorials.

Unfortunately I haven't used it either, so I can't answer your questions on this. I don't have a personal need for any windows apps on my machines, outside of steam games.

Wine is a compatibility layer, it works as a translator to let windows programs run on linux. You can think of it like having a translator who allows two people with different languages to talk to each other and work together.

WinBoat is completely different, this is actually running full windows in the background, and then only displaying the apps you want from it. There will be significantly more system resources used, and you won't be able to run windows apps until the windows VM has started in the background, adding a startup delay. However the advantage is that it will support more software than wine does, with fewer issues.

Wine will always be the better option when it works, but for stuff that doesn't work this is a decent option.

The 3D stuff around games is actually the smaller problem. It's performance critical but it's basically "just" one API (bundle) to implement that then covers a big chunk of the game's implementation.

Productivity software usually consists of a shit ton of other stuff. They would probably render fine, but then they ship with a weird ass licensing management system that will deny to work. Or parts of or even a whole app use .NET and suddenly you have the complexity of all the WinAPI calls hidden behind .NET Framework. Maybe the app does a few lowlevel WinAPI calls themselves on top, that Wine didn't need to implement so far. Or the app you want to run is only distributed via Windows Store as UWP; the necessary APIs also haven't been implemented yet.

Wine is awesome, but it's not fully covering all the shit Window's APIs offer.