Regarding 1: I can confirm that significant work is already being done on improving the UI and UX of gmx.io and the GMX dApp.
Regarding 2: additional use cases for the GMX token are indeed not part of this dev outline, but there are ongoing discussions about how to potentially optimise that. In terms of benefits to the token, the impending GMX-Solana deployment and its approach of Buyback & Distribute will be a key driver imho.