The first question is very interesting, i been thinking about this spot as well. Looking forward to read what Teunuss have to say about it. Is very difficult to adjust calling ranges to the right frequencies in multi way pots, i probably end up over folding in this sort of situations..

-You do mean the potential river decision right? Given it's 3way his flop cbet should be lower, and in general slightly stronger, therefore we don't have to defend nearly as much. But I think it's hard myself too, to give a defnite answer here.
This exact spot is going to be really hard for the SB, as how most peoples ranges are constructed in the sb, the sb will not have that many obvious bluffcatch hands, and will have alot of fairly weak valuehands like Kx.
The only obvious bluffcatchers will be A2s/A7s, which I will have 5 or 6 combinations off.
And we will have lots of Kx combo's, so therefore I felt like we have to defend A3-A9s combo's that we peel on the flop, because those hands dont block potential bluffs and are the highest in our range. Even with this strategy our fold frequency might still be too high in theory.
Hopefully that answer satisfies you ;)

-I agree with you that AK and AQ are fairly similar, but there is certainly a small x% chance that he will valuejam weaker than AK, but like I said, because I think this board will favour the IP player, I will do a lot of checking on this flop, and I defenitely prefer other hands as a bluffcatch, like the QTs/QJs/KJ/KT, and the obvious strong hands in my range that I decide to slowplay.
Edit: looks like PIO agrees with me on this one :)

Thanks for your questions!

Actually I am talking about the flop defense. Like 2way we have the 1-a as a guideline which we can deviate from, but 3way I have no clue how much to defend on flops.

I think once you call flop, the 2 ranges are set and turn/river should be played as a 2way game again with often 1-a frequencies like in normal 2way pots. Like the flop action determines with what ranges 2 players out of 3 get to the turn with, but after that it is a 2way game again game theory speaking right?

Thanks!
Well if I look at my current range, I will have a fairly high raising frequency of around 55% and I can easily defend half of that range to 3bets, so exploitation preflop will by being limp reraised a ton is not an issue.
This polarized strategy makes my range much more playable, because the really weak hands are tough to play as a check as we hardly ever realize their equity. By raising them preflop we realize our fold equity and we have the initiative in the hand, which increases R% by alot over checking it preflop. So I think raising the really weak hands preflop makes a lot of sense, and checking hands that are in between like a Q7s/K9o type of hand, makes our checkrange very playable too.

-I dont want to bluff Khighs/Ahigh hands because we are likely to overbluff and still have some showdown value, as he certainly checks down a number of Khigh that we beat.

-100% agree with you here, looks like a mistake by him.

-Listening back that part, I should have been more clear, I meant both turn and river play: so he is clearly always folding AQ to a turnbet+river shove, on the vast majority of runouts. So we are indeed folding out 77-99 on the turn and AQ by the river, which most likely makes up a very large portion of his range when the action is check/check flop.

Yes, or just bring in couple of examples during a live play review which was pretty good to watch in part 1 i think.