Nothing that exists today is moving behind a closed-source model. Omnisharp will continue to be open and maintained but it won't be the default anymore.
SourceTree doesn't track use/interaction information unless the setting is enabled. You can disable it via the "Help improve SourceTree by sending data about your usage" in the "General" tab in the options screen. If enabled, you can read about the exact data we send here:
https://confluence.atlassian.com/sourcetreekb/sourcetree-ana...
That's correct -- we chose to do this because it allows users to install ST without admin privileges. We use Squirrel, which is an incredible library btw (https://github.com/Squirrel/Squirrel.Windows)