A place for my dumb questions

Hello! Prior Reddit user here attempting to gain a better understanding of kbin and the Fediverse. Any feedback from more experienced users would be greatly appreciated regarding the following questions:

(1) Can someone explain exactly what an instance is?

(2) Is kbin.social a single "instance" hosted on a single server?

(3) How does one go about hosting or creating a new instance of kbin?

(4) What's the difference between Mastodon, Lemmy and kbin.social?

(5) If I've created an account on kbin.social, and kbin.social goes down or gets deleted, is my account also deleted from the Fediverse?

(6) Can user accounts be "ported" or "transferred" across instances?

(7) Does the content or Magazines created on one instance disappear if that instance goes down or gets deleted?

(8) If the answer to #7, above, is, "Yes", is there not a function or ability for other instances or sites within the Fediverse to constantly mirror or backup other instances?

(9) Do the threads I see posted on a Magazine hosted on kbin.social also appear in the same Magazine on Mastodon or other kbin instances?

Thanks in advance for any responses and answers!