So Kat was definitely making a jab at Alicia. Alicia's reaction was over the top, but it was a thinly-veiled insult from Kat, make no mistake.
I see how someone could view it that way, but I definitely don't think that's how it was meant. I think Kat was simply saying that she's horrible at puzzles and unless Alicia is some kind of puzzle wiz, she needed to be paired with someone who is. IMO, suggesting someone might not be a wiz at puzzles isn't a jab especially when it turns out that person is actually pretty horrific at solving them. I'd even go so far as to say it just isn't a jab period. I have a horrid singing voice. If someone says, "you're not the best singer" they'd be telling the truth, and it would be silly for me to be offended.
Once the tribes are merged, it's expected they will share with each other what they have, not still cling to what "we" won versus what "you" didn't win. What if they merged into one or the others' shelter? Would Jay say "Sorry, we built this shelter, you can go build your own" after a merge?
To me, that's apples and oranges. It didn't appear they had much coffee left and they were sharing what was left amongst those who'd actually won it. Since Tarzan was the only one who said anything about it, I imagine there was some conversation in which the others respected that it was their coffee. Plus, coffee is a treat. It's not the same as shelter, something they all need and would be a real hardship if it were denied. Lastly, if pissing off Tarzan is bad gameplay then I suspect everyone is playing badly. What Kim or Chelsea did (i get the two confused) and said in reaction to Tarzan's shitty drawers was a lot more confrontational than denying him a cup of joe.