Due to a pending transfer at work, I will have a bit of time off in early May (1st - 18th). I want to use this time to get to Melbourne (originating in LIT) and see my dad, who is in poor health. I went in October on a paid ticket thinking it would be my last chance to see him for a long time. Combine free time, family in Melbourne and about 200k in AA miles and reading too many trip reports on FT and I've come up with a plan, lol.

There is extremely limited availability in business or first to get to Australia on such short notice. I'm willing to take a circuitous route in order to fly a premium cabin, and try something new. My trip on October was in J on the QF A380. This is what I've found and currently have on hold:

Using 50k Business Saver, depart May 4th:
LIT-ORD-YYZ-LHR: first two legs are on AA, YYZ-LHR is BA J on the 744 and arrives about 9:30 am on the 5th. Then:

QF10 in first on the A380 LHR-DXB-MEL

This has me with about a 12 hour layover in LHR.

To get home, depart May 14th:
MEL-SYD-LAX-JFK. QF107 on the TPAC. Then overnight at JFK, leave the morning of the 15th and go JFK-DCA-LIT with the last leg on US.

It's a lot of flying! The traditional routes don't have any availability, so this appears the only way. I did some preliminary checking on CX availability to possibly route through HKG, but doesn't look good. I don't want to wait in hopes something else opens up and lose what I have now. Couple of questions though:

Biggest question: I currently have these held as two separate itins on AA. Assuming I book before the hold expires, I am good on the award availability, correct? I don't want to assume it is held then lose the award seat!

Secondary questions:
1) Do I have to clear customs/immigration in YYZ if I'm only connecting through? What about LHR? Can I explore London for the day?
2) What lounge access will I have in LHR? (AA plat for what it's worth)
3) Any suggestions on something to do in London with a full day layover?
4) Any easy, reasonably inexpensive, say sub $150, airport hotels at JFK?
5) Anything else I'm not considering?

This will burn off all of my AA miles, which I'm ok with. I likely won't be able to take time off again for quite some time, and I truly enjoy flying, like many of you. I'm excited to fly two different 744s in J before they're retired, plus the chance to experience QF F on the A380.