The non kosher beer isn't actually non kosher-its just a chshash.
The vats are huge, and even though most keilim don't hold 60 times kneged their walls, these probably do. Even at a small brewpub, the vats are still many times larger than a kitchen pot.
Most of the beer they sell wasn't made within 24 hours of a nonkosher batch.
It doesn't actually taste treif. We know that through tasting by an expert, b'mesiach l'fi tumo, because there's a guy whose job it is to make sure it all tastes correct, and if it tasted different based on what was made before, they'd fix that. Beer is not potato chips--people are experts in tasting it and knowing if it tastes different.
I'll address your points one by one
I'll preface by noting your previous point (a pet peeve of mine). Just because you can't certify a facility based on a number of lechatchilah reasons, (as per Igros Moshe "mechu'ar hadavar" by bitul) doesn't mean the public can't consume said item al pi shu"a. Case in point, advising the public not to consume cols brewed coffee since it may be kavush in assur keilim, is a blatant disregard of the pesak of the Sha"ch that even though we are machmir lechatchila, once it was kavush we are meikal as the sevara is lekula.
As per your points,
1. There are non kosher flavored beers- first hand knowledge
2. correct as far as I've seen regarding vats but there is other equipment that the beer is certainly not 60 x the kli
3. I'm unsure . I'll check into that
4a. It may be so but ashkenazim dont rely on te'imah (as per the rem"a ) even bedi'eved (except in certain instances- possibly a yisrael regarding teruma- see the shach)
4b. while you may think that the breweries care more about the correct taste than the potato chip manufacturer, the potato chip /cookie / ice cream manufacturer certainly cares very about the taste to the point that most of them taste every batch
regardless we can't just decide to reky on te'ima.