Second Switch/Island?

Hi everyone! I bought a second switch off of a friend and I’d love to use it to make a second island - SO my questions are:

-Will I need to buy a second copy of the ACNH game? Or can I use the downloaded game from my first switch and download it onto my second switch? -Will I need to have a separate Nintendo Online subscription in order to have a separate island? Or can I use my main Nintendo Online subscription for both?

TIA for any help! ☺️