I have an upcoming trip business class trip to Korea and Mongolia, in the middle of winter no less, for HKG-ICN//ICN-ULN (KE codeshare, MIAT/OM metal), ULN-ICN-HKG

For context I am OWE and almost exclusively fly on oneworld airlines, probably around 30 flights a year in business/first. However, no viable oneworld/CX option really existed for this trip, so thought I'd try something new.

I did a few searches, but didn't really get a definitive answer, any thoughts would be welcome on the following:
1. Seating... as this was a business trip booked at pretty short notice (2 weeks in advance) I've ended up with fairly rubbish seats, on what seat like fairly old planes. Particularly unpleasant having 2-3-2 business on the HKG-ICN leg which is the redeye KE 2012 /00:55 departure. I did look at paid upgrades into the unused "First class" cabin but they all seem to be taken, or aren't available to buy, nor does ExpertFlyer show them as available. The other 2 flights that day were fully sold out in business too(!). I have zero SkyTeam status, but seems I am going to be lucky enough to get an aisle seat rather than the middle of a 232 seat set-up or right at the back of the cabin. I did set up ExpertFlyer alerts for windows. Is that typical to be stuck with few seat choices; should I try diarising check-in to try and get some blocked seats that are elites only?

2a. Codeshare lounge on the KE codeshare/MIAT metal: From looking online, seems I will be stuck with whatever MIAT gives me in ICN?
2b. KE Lounge (~3 hours at ICN in transit): Seems there are new ICN lounges, lucky me. How worthwhile is it me wandering the terminal to lounge hop, or is there one to just head towards the one nearest my gate?

3. Food - I see a number of pre-orders available. Typically I choose whatever is on the flight and am not that fussy - but I am also the lowest status passenger and my preferred CX always takes OWE orders first, so I get my first choice. So is it likely that my KE food choices wouldn't be available, aka I should pre-order something?

4. The HKG-ICN redeye, considering it is such little time on the plane, I have no idea if there will be much in the way of quiet time, in-flight bedding, or if I should expect the (seemingly full) service will take up much of the first hour or two anyway, potentially with my seat-mate(s) wanting to eat & drink. Aka, maybe I should just plan to be aware and eat/drink (and sleep before/after, I have a hotel when I arrive in Seoul, though know its a long way to get into the city). Thoughts on what to expect would be welcome?

Anything else worthwhile being aware of, I realise that this is only a regional flight and on a hodgepodge of planes, plus this was my last flight on MIAT (KE doesn't fly every day to UB). My last KE flight was a long time ago, think I only did a domestic hop to Jeju.