Re: anxiety at the point of changing my domain name from .com to.org
You can register a new domain name as .org and set that up as the websites domain name, and it can indeed be done seamlessly.
However, you cannot "change" a domain name itself, a .com domain name is a completely different, distinct legal entity from the registration of an identical .org domain. Each is purchased via lease from different registration companies, so they can't be switched-between. Every domain registration is its own purchase.