Blocking someone means that you don't want to interact with them anymore and making all of your content invisible to them is a pretty surefire way of doing that.
I'm not sure what you mean by "Advanced Search -URL" but on Kbin you can put federated #links on the search bar to get (or create) the Kbin version. It works with microblogs, threads and comments.
Thanks for the insight! I was mainly wondering about how I should use hashtags on my own microblogs and comments but I didn't even think about using them as browsing tools. Could you maybe give more tips about the former?