You can compile to many formats, if that is what you want to do to be extra sure of keeping the files. Plain text will wipe out any bold, italic, underline, and so on, formatting. You might find rtf is a better choice. But there is also html, odt, word doc, docx, and so on…
You should also look into sync. Set up sync with external folder (either as plain text or rtf exporting) and have that take place whenever you close the project. I think you can also sync non-draft files.
Your research files you can treat in a number of ways. If they are capable of being converted to Scrivener text, you can bring them into your draft (at the end). They will then surely be subject to the Sync like any other part of your draft, or you can include them in your compile. But you can also export the research files if they cannot be converted - a sound recording, for example.
For research, much of what most of us gather comes from outside sources, and we don’t edit them much. So these research files can be saved outside your Scrivener project before you even bring them into Scrivener. That is: when you import that video file or PDF, the original stays where it was before you imported it. These files you already have.
I also recommend turning on automatic backups, as zip compressed files. Copy each of these onto other media.
If you plan on going straight from Scrivener into a publishable format, into Amazon Kindle or pdf for example, compile is a good way to go at the end of each day’s session, or at any particular milestone in the project. This gives you a non-Scriv backup that also tests how the work will look in that format.
Remember also that you can always right-click or control-click on a scrivener project in the Finder and “Show Package Contents” and copy out of the project the texts and files in their native format. But this is tricky unless you know what you are doing.