I don’t have any specific recommendations, you’ll need to decide how the various providers match up to your ethical requirements. You say you just want to “try out some things with a secondary domain”, so you may want to take the opportunity to test a few of the services to see which suits you best.

WDYM by “hostname”?

In terms of DNS, a hostname is just the name that you want to be able to resolve to an IP address, so, for instance www.google.con is a hostname in the google.com domain. Because the system is hierarchical, google.com can also be a hostname in the com domain. Specifically, a hostname is represented by an A record in the domain, and a nested, or sub, domain is represented by a NS record, with similar types for IPv6 addresses.