Hosting the Leading Websites:
You can have a bunch of domains at one host, but find out how much you’ll pay. At some Web hosts, having domains is free as long as you already have a website there. But, possibly, for all I know, perhaps other Web hosts require a website or equivalent for each domain. Some Web hosts do limit how many domains you can have with one account. That could get pricey. You could need more domains than websites if, for example, you have defensive registrations or you buy domains before you set up websites for them, such as by arranging for newly bought domains to point to existing websites of yours until you develop websites meant for those domains.
You can probably buy a domain through a Web host, but, if not, you can buy one through a registrar or a reseller, and there are many. Even if the host sells domains, you usually don’t have to buy through the host. Some hosts might require it, but you can switch hosts. If the host tries to force you to use only domains they supply, even if one is free, if you need another it could be expensive, transferring it could be costly or difficult, or using redundant website hosts for one domain for service reliability may be problematic. It’s okay for a Web host to offer domains as long as you have the choice to get yours elsewhere.
If a specific top-level domain (TLD) is of interest to you for registering a domain and if you want to contact the top organization responsible for that TLD, you may use the contacts linked to on http://www.iana.org/domains/root/db (except that for *.int see http://www.iana.org/domains/int and for *.arpa see http://www.iana.org/domains/arpa) (all three were as accessed ).
Which is the best registrar or reseller is beyond my knowledge. A list of registrars approved by ICANN and their contact information is at https://www.icann.org/registrar-reports/accreditation-qualified-list.html (as accessed ). To find a reseller, especially since resellers might offer better pricing or service, since resellers probably have contracts with particular registrars, contact a registrar to find out who their resellers are.
Once you own a domain, it’s most likely you can use it through the Web host of your choice. Very few hosts would want to refuse.
A website technically must run before you buy the domain, in all likelihood, but you don’t have to have content or a design before getting the domain, and probably shouldn’t. That’s because you may need two IP addresses for your website at the moment you register the domain and your website host provides the IP addresses, even if the website is empty. An empty website can be set up to display a blank page, a page that says there’s nothing here, or a parking page (supplied by some hosts) of advertising (although you might not earn any income from the ads).