HS can mean anything you want! Originally, we were Homestuck.gs, but you can use your imagination! It doesn't have to mean anything!
We are a daughter-site of Meulin, which is a HSPro Web Groups site.
Sure! Any domain, 4 letters and up, is free. Drop an email to leijon@meul.in with the domain you want. We're very flexible. We can point your domain to a site like Tumblr as an A-Record, or embed it on our server! 3 letter domains and shorter will cost a small fee, due to the exclusivity. It's a very reasonable charge.