Does it autoupdate?
Yes, it does very much so (20+)
If you use Docker No. https://documentation.storj.io/setup/cli/software-updates
If you use the Win Installer Yes. (Check Taskmanager for storagenode-updater.exe)
Doesn’t watchtower run on Windows too?
You need watchtower running on docker. Windows has a service running to do the update. Almost seamless. I like the windows version over docker.