You'll find in local stores. No need to order from Nintendo online. I wouldn't be worried on getting the English variant tbh.

Found the underwater stuff to be decent till Tom Cruise did...that to get out of torpedo shaft. That was...just lame. Not just suspension of disbelief but also physics. 1st 30 mins were absolute snooze fest. Still kinda enjoyed FWIW.

I hope so but even for the English one there is a lottery system, maybe the hype dies down a bit in a couple of weeks.

No discount for existing subs.

If you're looking to get the English variant, it should be in stock easily. The Japanese cheaper variant will likely be OOS. Don't think so. Good news is Nintendo has confirmed release in SEA countries on 26th June. So should be available in TH, MY, SG, PH etc. HK release is 5th June anyway. Should see imports from these countries soon.