The simplest way to change visudo editor from nano to vi
If you are using ubuntu or debian, the answer is
sudo apt purge nano
It is not a joke, it works! Reference
Surely there is a regular way
sudo update-alternatives --config editor
which is also good. But I love the former way, as it also removes the nano editor, which I nearly never use.
how to do sudo without asking a password
sudo visudo, then add a line at the end of the editor
your-user-name ALL=(ALL:ALL) NOPASSWD:ALL
save and exit, done!