I'd have to go back and review a lot of the examples you've given. The only one I can speak on, off the top of my head, would be the scene in The Trouble With Tribbles. And then I just thought that those adorable, cooing little creatures were so alluring that they even penetrated Spock's tough hide. However, there are more examples in TOS that showed Spock to be in total denial of his human half. IMO, he rejected it most ferociously, so I stick with my conclusion of total emotional repression.
TOS Spock was in denial of his human half or at least trying to deny it as much as he could. But at the same time, there were plenty of times when he showed emotions in a subtle way, sometimes even less subtly when he would lose control for a moment (not counting all the episodes when he would lose control for a longer period of time due to outside forces or Pon Farr), e.g. when he suddenly changes his 'we shouldn't hurt the Horta' stance once he realizes Kirk's life is really in danger and starts yelling to Kirk to kill it. As diftorhehsmusma said, he would show glimpses of emotions despite himself. A person may try to be as unemotional as possible, but that doesn't mean that they'll actually manage to erase emotion or even always hide it from others. In TOS, the audience were constantly presented with the contrast between Spock's insistence that he had no emotions, and hints that this was actually not the case at all, and this was a source of a lot of comedic moments, as well as poignant, sad and moving moments. Some of the other characters in TOS seemed to realize that, as well - Kirk always seemed to be quietly aware of it, Chapel understood it (her speech in "The Naked Time" shows), and even McCoy occasionally showed that he realized Spock was suppressing emotions rather than actually devoid of them ("Bread and Circuses"), and this gave rise to many moments when McCoy, Kirk and other crewmemers would tease Spock and try to make him admit he had had an emotional reaction (as in "The Galileo Seven").
We barely ever saw TOS Spock interact with Vulcans, apart from his father, briefly during Pon Farr with T'Pring and T'Pau (who basically asked him at one point to prove he was a true Vulcan) and a spectre of Surak in "Savage Curtain". It is quite possible that, while humans in the Starfleet saw Spock as cold and logical, an average Vulcan might have seen him as too emotional. I'm watching season 1 of Voyager, and at least at this point (I haven't seen the rest of VOY), I can't see Tuvok engaging in sarcastic banter with any of the crew the way TOS Spock always did with McCoy. TOS Spock also had more warmth and considerably more of a sense of humor.
And what difference does it make what he showed as a child or a teenager? Do you really think Spock Prime had self-control as a child, or that any Vulcan child ever had that kind of control? We're talking about children.
Yes. I think as a child (and a teenager) Spock Prime went out of his way to be a stoic, unemotional Vulcan because of his relationship with Sarek (as alluded to in TOS).
The issue if not whether he went out of his way to be a stoic, unemotional Vulcan. The issue is how
successful he was in that attempt. Do you know any children and teenagers who were already as much in control and exactly the same as they were as adults? That's what adolescence in all about - not just physical development and transformation, but a fundamental change and transformation of personality as well. This is why it is such a troubled and painful stage in life. There's no absolutely no reason to think that this is different with humanoid alien children. In fact, Vulcan children we see in ST09 or in TAS episode "Yesteryear" suggest that Vulcans are in that respect, same as humans.
And, as diftorhehsmusma noted, in ST09, little nuSpock was clearly doing his best to be a stoic, unemotional Vulcan. It took 35 attempts for the bullies to make him lose control. And once he did lose it, he had an explosive, volcanic (pun intended) reaction - a consequence of suppressesing and denying your emotions to such an extent. Little Spock was provoked by the bullies in a similar way in D.C.Fontana-written "Yesteryear" (the episode that is, BTW, considered canon because its events were referenced in TNG). In fact, little nuSpock showed more restraint and seemed to be less easily provoked than "Yesteryear" little PrimeSpock.
Let's also not forget that Sarek in TNG "Unification" says about Prime Spock "He was always so
impressionable..." It seems that Spock's father always saw Spock as a very emotional being.
Is nuSpock really that different, for the first 3/4 or so of the film? He is also doing his best to suppress emotions, and showing them only despite himself. And when Kirk provokes him, he reacts violently, just like an emotional person who suppresses their emotions all the time would. Just like Spock Prime when provoked by Kirk in "This Side of Paradise" (no, this example can't be dismissed with "he was under the influence of spores" - because the spores were actually making him less likely to be easily provoked into anger and violence - which is why it took Kirk so much to succesfully goad him into the fight), or betrayed by Valeris in Undiscovered Country, or when insulted by Scotty in "Day of the Dove" or McCoy in "All Our Yesterdays". OK, now I know in these last two examples he was also more violent due to outside influences, but I think having had your planet destroyed and your mother die in front of your eyes also qualifies as abnormal circumstances that can make one emotionally compromised. And in none of these circumstances did Spock choose to act that way, it happened in spite of himself. It's not like he chose to have a violent emotional outburst, and it says nothing about his decision to be stoic and unemotional. Kissing Uhura in the transponder, or calling Kirk "Jim", these things show that Spock is more accepting of his human side and his emotions, not his outburst against Kirk - and they both happen
after Spock's hear-to-heart conversation with his father in which Sarek admits he loved Amanda.
The main reason why you won't convince me that nuSpock, before that, was comfortable enough with his emotions to have a full-blown relationship with Uhura, is because what we see in the movie does not support it. Before the transponder scene, we saw Spock:
1) try to assign Uhura to another ship, for fear that people would see it as favoritism - even though he is actually aware that she is the best qualified person for the job on Enterprise. This shows that he was very uneasy with having any kind of close relationship with her; and that he was perhaps also trying to keep her at arms' length.
2) when he was being comforted by Uhura in the turbolift - he only briefly accepted her hug and kissed her, very uncomfortably, before pushing her away and insisting that what he needs is "for everyone to continue performing admirably". And that was
in private, when nobody was watching them (and at a moment when he really, really needed some comfort and affection). This is not a person who is comfortable having a relationship. This is someone who is very emotionally repressed. In fact, this scene and the one in the transponder are very much in contrast with each other.