>>58760The default My Filters tab should be blank, I can't recall from memory, but - ask Raymond Hill aka gorhill to be sure on github - it should support that much, yes. Again as Anon said, whenever you block something with the inspect tool, it will be added with a comment on top (a "rule" with an exclamation mark to denote the rule as ignored and the timestamp among other things). That could easily add up to 9000 lines over time.
The whitelist area is reserved for full-scale whitelists, just let the defaults in this unless you have a strong reason to whitelist an entire domain. It's defaulted to browser schemes. Hope this helps!