a) please, don't embarrass yourself. They are the same person. They look the same. The AI clearly took the kid persona by reading Shep's mind somehow (at least that's probably the writer's idea).
I know they look the same. I'm not an idiot. I'm just telling you that they're not the same person. The kid died on Earth, Shepard saw him die and it affected him and he had nightmares of him (Which I believe were indoctrination attempts,but where not here to talk about this and also the kid as nothing to do with it). Like you said, the Catalyst clearly took this form by reading Shep's mind (this kind of thing happened 2 or 3 times in series), but not to trick Shep or anything like that. It only took this form because it needed to manifest as something Shep would understand. Also because this kid sort of represented everything that was going on on Earth for Shep.
b.) It is bad writing to abuse the kid for an endless monologue trying to explain things 10 minutes before the end of the game. I'm not even talking about what he says, but the fact that it is there at all. The story didn't really need the synthesis or control ending at all, but I could accept them being there when they had not messed up the destroy ending so badly. The motive of the story was overcoming the impossible by overcoming the differences between (races), and friendship. Now, since the Control & Synthesis solution is clearly retarded, the only logical conclusion to the story is the Destroy Ending - which the writers screwed up by basically telling the players: "screw you, you worked so hard to make peace between the Geth and Quarians, and EDI being Joker's LI, we'll just ruin your day now by rendering all that work meaningless." - That's what bad writers do, they think more character deaths makes for a better story.
Well the story has Synthesis and Control because they were built in Crucible several cycles ago. They're part of the story whether you like it or not. No one is forcing you to agree to using those choices, but they're there and they will always be.
The writers did not screw up Destroy. There are casualites in a war. Necessary sacrifices. I know it sucks that you lose the Geth after you achieved peace between them and the Quarians, but it's part of the choice. Same goes for EDI.
e) My pity goes to you as well for dishonestly proclaiming "Anybody who doesn't like the ending is too stupid to understand its genius.".
Whoa there! Don't put words in my mouth. I never said that.
First of all: I'm not saying everyone should like the ending. You have the right not to like it, but don't go around saying that the endings are ''retarted'', that it's bad writting, that it should all be changed and that parts of the lore should be removed because you didn't like them. The story was written this way, accept it or move on with your life.
Secondly, I'm not saying anyone is stupid for not liking the ending. I'm saying that most people don't like it because they simply didn't undertand it. That doesn't make you stupid.
Anyways, I would recommend you read this: http://forum.bioware...-leviathan-dlc/
I certainly hope you do, as this might help you understand the Catalyst better. I know it's a big wall of text, but it's worth the time.