I know this probably a dumb question, but do I have to use a text editor or can I just work right inside visual studio?

If its just for text editing, then you can work inside Visual Studio without any issues/changes.
But if you will want to build HandmadeHero code in Visual Studio IDE with solution/project then you'll need to do few things in special way (or avoid them), like unity builds and live code reloading.

Fair enough, thank you!