Soldato
Pretty sure if it's installed on the system it's there for everyone. I've got multiple accounts and they can all see and use the same content.
When you start a game it even prompts you asking which account you want to use before it launches.
Correct
Sounds great, but its a pain in the bum if your switch ever gets lost or broken.
The digital games are primarily tied to the machine, your account is just a tool to facilitate the download.