Games and accounts are Region-free but they are tied to only one account; you cannot launch a game purchased from one account when using another account.
Yes you can if they are on the same system. It's what I do to keep different saves of the same game when I let my brother and sister play botw and other games. Just checked by loading one of my games from my US account with my Japan account
Since I believe you can't connect to online on lower firmware, you can do it from accounts.nintendo.com, sign in, go to shop menu, then deregister primary console. Note that you can only do this once in a 12 month period.
No that unlinks your account from that switch. Which includes eshop access. Then the next switch you sign into eshop for will become the primary console (the one the account is linked to)
You may be able to try to call nintendo to do something, but it's not a guarantee they will do anything about it.
Account linkage is server side. Deleting the local account has nothing to do with it.
No, I was serious. The FAQ recommends sx os, and for some reason doesn't even mention atmosphere or rajnx. Where can I find more up to date guide about different cfws?
