I am a Australian PR holder hold a Sri Lanka

Hi, I hold an Australian PR with a Sri Lankan passport. My brother lives in HongKong. We want to travel for 3 days, go to Sri Lanka. Our transit returning to Melbourne is via Hong Kong. 1. Do I need to submit application with my passport? 2. Do I need to get my brother to sponsor me? 3. Do I need to get transit visa since I am traveling back to Melbourne via Hong Kong?