Curiosity – 1. Forgive me but if it is the bending that’s undignified then the dimyon to horses doesn’t work. Horses can’t bend down as they don’t stand upright. They drink by lowering their head, by partially kneeling so that the front of their bodies is lower than the back or by kneeling fully to bring their head to the water level. I therefore assumed that the dimyon to horses was to the manner in which they drink, i.e. lapping. This is also the way one drinks from a water fountain, and the manner of drinking of the soldiers who were kept (regardless of whether they were sitting, standing, bending, lying down or jumping around no-one disputes the lapping). This also answers your fourth point.
2. Don’t tell me what I am and aren’t expecting to do. What I was doing was pointing out the difficulties, which, unless you believe it’s assur to ask kashas on a shitta you don’t understand, is a perfectly reasonable thing to do. Given the difficulties, and given that it’s a da’as yochid that all the other mefarshim disagree with, forgive me for learning like the other mefarshim. Furthermore, if you have answers, please provide them. Don’t just sit there like a 4-year-old saying “I do know, but I’m not telling…”
3. The only reason that the Mahari Kara talks about those standing is because he has to create a 3rd group given as he can’t have the 1st group being chosen as he believes that they too knelt. He is therefore forced to create a 3rd group which he says “could have drunk standing”. None of the other mefarshim have his problem, none have any more than 2 groups – those that knelt and those that lapped – and therefore none learn like the Mahari Kara. Nowhere are any of them mashma, like you claim, farkert. The Ralbag, as pointed out, says b’feirush that they were chosen as lapping from the river showed their fearlessness. The Minchas Shai has 2 groups, those that knelt and drank from the river directly and those that drank from their hands (he is medayek “min hamayim” as opposed to “al hamayim”), which seems to indicate that this was the only difference between the two groups, mashmaus is that those that drank from their hands also knelt (in other words the kneeling was not indicative of avodah zorah, the manner of their lapping showed whether they had discipline, though both still lapped).