If what you're after is a single file where you can keep an eye on different versions of the content, you could perhaps call on styles: could take a while to set up, but then you could have (for example) bodyText_latest and bodyText_lastweek using different colours. Once that's working, pause for a good breakfast and explore the find/replace options for deletion using styles.
You could also apply colour/font changes by hand, though that take a bit longer to manage when you wanted to make a clean final version.
Just out of curiosity – I've heard about various word-processors designed specifically for writing scripts/fiction. Have you come across any of them?