What's this about Scott betraying Derek? He never intentionally did that. In 2x12 Master Plan he specifically said he did what he had to do to protect his mother, becoming a mole in Derek's pack and getting close to Gerard so he could undermine him. In 2x04, he did complain about the lack of trust in everyone around, and did keep Derek out of the loop but that's hardly any grounds to label him a hypocrite, case in point of Derek's hotheadedness and decisions at the start of season 2, which cost him Scott's trust in the first place. I'm not saying Scott isn't foolhardy or isn't too trusting sometimes, he's simply looking out for his own interests and those of whom he cares for in the moment.
I'd say Scott never intended to outright kill Gerard, even though the old guy is an irredeemable psychopath, he was holding Allison hostage using the Kanima at the time. Scott told Stiles in 5x13 he knows what self-defense is, which was clearly the case with Gerard. He knows when mercy and forgiveness is due, as was it with Deucalion, and was willing to kill Jennifer because she was about to sacrifice his mother. Scott just doesn't believe in outright murdering people, even if they are a monster, that it shouldn't be the first option. I'm sure Scott's aware of the morally gray characters around him, but shouldn't the personality section of him just detail his view of what is moral and what's isn't, not comparing his morality to others
Betray - to give information about (a person, group, country, etc.) to an enemy.
Whether he wanted to do it or not, it is still an accurate description of what he actually did. If he had wanted to play along with Gerard without betraying Derek, then he would have had to let Derek know what was going on and they could have worked together on fooling Gerard instead of going behind Derek's back. That was an option that was available to Scott, but he did not choose to do that. Incidentally, be wary of people who say they “had to do” something. It’s been used to justify all sorts of horrible things throughout history when there are always other options, even if some of those are unpleasant, that don’t compromise their morality.
So it is a fact that Scott did betray Derek and whether he was justified or not in doing so is up to each viewer to determine for themselves based on their own interpretation of his motives and the other possibilities open to him, as well as any personal bias toward him. We forgive things in friends and people we like that we would not forgive in strangers or in people we view as competing against those we like, which is not a moral failing but an accurate depiction of how emotions play into morality.
Scott being hypocritical on trust has nothing to do with Derek's (or anyone else's) actions, only Scott's own actions and words. If Scott wanted people he considered to be allies to trust each other, then it was up to him to make that first move and be consistent about it regardless of whether the others returned that trust. On the other hand, if he doesn't consider someone to be worthy of his trust, then he should not expect them to trust him either.
I probably don't need to mention this part, but just for the sake of completeness - "he's simply looking out for his own interests and those of whom he cares for in the moment" don't forget that this applies to all the other characters too. Scott, Derek, Stiles, Lydia, Peter, and even Gerard. All people look out for their own interests and people/things they care about regardless of whether their actions are good, bad, or somewhere in between.
There are different ways to murder people other than more direct and immediate means. Deaton and Scott replaced Gerard's cancer medicine with mountain ash which alone would have increased the chances of him dying even if it would take a while, just like slipping poison into someone's food over a period of time. Add on that they knew Gerard wanted to get the bite to cure his cancer means they were planning to have him reject the bite, something that they know usually results in death. It seems to be a fluke that Gerard survived at all. The self defense justification usually comes into play in situations of immediate danger, but this was planned in advanced. It's a bad guy, so we don't feel particularly bad about it, but it does go against some of what Scott says and the line that he wants the people around him to follow. He has become more aware of this in season 5 and softened his stance accordingly.
"Scott just doesn't believe in outright murdering people, even if they are a monster, that it shouldn't be the first option." That is currently true in the more recent episodes, but has not always been true - which is the point of these examples.
Some of the beautiful things about Teen Wolf are that the characters change, have flaws, and are unreliable narrators. All of the characters present themselves in the best light, but it's up to us to analyze their actions independently of what the characters would have us think of themselves and the others around them. One of the trickier things is that this also applies to the narrative of the show as a whole. It has its own bias and we, the audience, must analyze it to determine what is what. For an example of narrative bias, we could rewrite the show from Peter's perspective and make him the hero without changing any of the events. "Man whose family was murdered seeks revenge" is the plot for quite a lot of movies, so it's not too difficult to do. So we have to be aware that the narrative is going to be biased towards Scott, as he is the focus character, and we have to question if he's really as good as the show presents him to be (and it isn't all or nothing, it can be a mix).
"[S]houldn't the personality section of him just detail his view of what is moral and what's isn't, not comparing his morality to others" - I don't think it is comparing his morality to others, just explaining where he meets or fails to meet his own moral standards/showing he does have faults. I don't spot any particular area that says "this is what Scott did while character x would have done this other thing," but let me know if I'm wrong.
Split the description of Scott's supernatural abilities and Scott's occasional issues with using those abilities into separate paragraphs. Using bullet points for the examples of the latter helps avoid being long-winded and aids in picking out each incident while reading.
"Later, when he becomes enamored with, then falls for Allison, and she with him, he impulsively/stubbornly ignores the complications of her parents being erstwhile hunters of werecreatures."
Impulsive tends to be more about singular decisions and not repeated ones. Stubbornly is the right word here as Scott makes a pattern of continuing to see Allison despite being told that is a bad idea multiple times from multiple different characters.