There a small discussion about it here - Preview and list of custom filter and the following link mentions it additon to Brave-Core.
As for the extensions, I think the ongoing research and improvements to the features post 1.0 will have many users deprecate their usage of uBo which also has the prevent ip leak, Privacy Badger and HTTPS Everywhere wouldn’t probably be installed by any Brave user seeing as it’s practically built into the browser itself. However, Decentralyces is probably the only privacy addition some users may use, though I haven’t used it myself.
I think they’re going to work on the mobile versions after they’ve worked on the Browser versions, so post 1.0. The timeline and roadmap isn’t as through and updated as their browser version, they just have snippets of information.