That would definitely do it. The installer should open the ports automatically, though.

Definitely your call, but be prepared for SW support to tell you to move to a supported OS if you ever need help directly from them. It’s not that it won’t work on 2019 (or 2016 for that matter) - it’s just that Spiceworks hasn’t tested it, so they don’t know if it will work or not.

Spiceworks Desktop is essentially on hold until they figure out the unified codebase, which is where a lot of the resources are going. That’s probably why they aren’t testing the current release on new OSes.