Setting-up VBox Debian or Linux lite or both?

So only if we’re setting up with a disk or iso we have to create the Debian template first and then upload? And if we do the download of Linux lite and windows7 through an ova we don’t have to worry about doing the additional Debian set-up in virtual box like I mentioned in first question?

The point about virtual machines is to use them as a learning tool. So for example. If you want to follow lectures on say Windows 10 you can install a Windows 10 guest to do that. It’s your choice what you want to install and do.