Apologies if this is the wrong place, as this is only tangentially United-related...

I was looking to clarify some things about making D/I and I/D connections in Australia (let's use SYD as an example). I know that domestic and int'l are basically two separate airports. Say I am flying SFO-SYD-BNE on a single United ticket, with SFO-SYD in UA J and SYD-BNE in QF Y (or really any carrier but QF seems to have the best service). I will always need to reclaim my bags to go through customs (I assume), and haul them myself to check in with QF. What effective baggage allowance do I get on the SYD-BNE segment? Do I just have bags tagged to BNE (according to my UA 1K in J allowance) that QF will scan? Do I have to conform to the QF domestic Y allowance? The QF Y allowance for SFO-BNE?

And then same questions for the return journey, checking bags in BNE. I assume I also have to manually cart them around at SYD, or is this transfer online? And what allowance, if flying UA J overwater?