The 4Pts will mark you as a no-show unless you annotate your reservation with the BA flight number, arrival time and you are still likely to have it processed as being for the next day (the hotel completes the billing cycle by about 3 am). Maybe you can book an internet prepaid rate?

As for returning through NRT, I was refused this as an illegal routing (I was trying to transit SYD-HKG-LAX in order to fly CX). The rules allow a 2nd arrival in Asia only for transit between Europe and SWP. This makes sense as there isn't a practical way to get there without going through Asia, whereas lots of Australia-NA service is available making it unnecessary to go through Asia. AA is notorious for checking RTW routings for validity and canceling illegal legs -- do a search on flyertalk and see all the BA segments that AA has canceled. You have a high chance of arriving in NRT and a diligent AA agent catching that your routing is illegal. This forces you to reissue the ticket and fly back to Australia at your own expense (note that surface trans-pacific is not allowed, so you cannot use the rest of the RTW until you have a valid pacific crossing, which appears to be only from SWP to NA for you). Is the risk worth it? You can fly QF as an AA codeshare (but cannot use VIP03 on codeshares).