Yes, this is currently only available for Team Create. To what end would you like to use this in a non-TC game? For editing by yourself, or for working with other developers that are changing scripts while you’re offline/etc?
It generally helps to provide as much information as possible when asking whether we will support a feature or not. Otherwise if we have something planned we won’t know if it addresses your needs (e.g. we only support non-TC for editing by yourself, but you want to edit in a team), and if we don’t have it planned, providing a compelling use case may just as well motivate us to support it.
No. There are some benefits like the ones you’ve mentioned, but the local edits+commit approach is more broadly useful. If you would like us to support live code editing as well, please make a feature request with as much information as possible.
Similarly, providing as much information as possible will make sure we are addressing your needs with any work towards these, or convince us to support these use cases if we already don’t. These particular features are a lot, so I would recommend making a feature request thread to discuss developer needs for these.