If I download a newer version of Audacity from “audacityteam.org” will it automatically replace the previously installed version?
If you install a new version the old version is normally replaced. (You can install it to a different folder but I think there will be some shared configuration files.)
…And the 64-bit version gets installed to different folder than the 32-bit version so they can both exist at the same time.
Thanks! 
But don’t run them at the same time … https://forum.audacityteam.org/t/sound-like-old-2011-recording/63926/6