Likewise, I'll have quite a number of CX to HKG flights resuming in Q4.
1. Assuming in-town check in is open (it wasn't when I was last there several months or so ago), I've always been able to get the courtesy channel (forgot what it was called) voucher irrespective of whether or not I was checking in luggage. Generally, I prefer to retrieve paper BPs here, often request an extra copy just for my jacket, even if I've already checked in and have the mobile one on my phone.
2. Ah, this is something I try to avoid, unless absolutely necessary. As with most airports not in the United States, they don't seem too enthused when one wants to leave the sterile area once inside. As to lounges, while surely a hotel would be more comfortable, I have spent many a nights in the Plaza Premium lounges which were open 24 hours. I suppose, enough soda, a comfortable cubicle, and outlet for my laptop makes it easy enough to pass the time before the CX lounges open up in the morning, at around 5 am.
3. Never tried this, but I don't see why?
4. Good question! You'd have to ask, because I had a situation where I was on a single PNR with BA connecting to AA, and BA during check in advised interline with AA on my itinerary was not available. So, maybe it's dependent on the first carrier, and if CX will interline, I'd verify it with them during check in.
5. Ah, my recent flights on CX have all been fine, and more or less as I had remembered. While there are I'm sure there are little things I can nitpick here and there, it really wasn't bad enough where I'd remember, like if they had lost my jacket. LOL Anyway, I'm glad it appears the burger is back on the HKG to NA routes, where it was missing during my last JFK - HKG flight. So, looking forward to my next flight and enjoying HK.
Have a great trip! I'm just ecstatic we're returning to some semblance of normalcy where I can just get a tix, go through e-chanel at HKG, hope on the AE, and just pop out of TST or HK station.