Rojo is only the filesystem-Studio sync portion; as said above you need an actual language server. Normally I just install whatever provided they don’t conflict with each other since there’s a lot of options available out there, lol.
To better work with Roblox code in VS Code I use the following extensions (they’re listed by id, you can pop them into the search bar in the extensions menu to see them):
- nightrains.robloxlsp (LSP)
- koihik.vscode-lua-format (document formatting)
- icrawl.discord-vscode (Discord rich presence, bonus I like to have to show I’m working)
As for the manual save, yeah it should be like that. It probably wouldn’t be best for your workspace if Rojo kept syncing uncommitted content to the environment. Ctrl + S is a handy shortcut, or you can create a keybind for the Save All command. Muscle memory just leads me to not do that and instead use Show All Commands (Ctrl + Shift + P) → Save All.