No to most of your questions. I've played with AI modding in other RTS', and the core system any AI operates with is based purely on defined values. While I don't know exactly how Sins AI is done, this is generally how RTS AI works:
Units/structures have various 'values' to the AI, and it bases its decisions to attack or keep building up based on its relative fleet 'value'. Smarter (ie cheating, but necessary cheating) AI will factor its enemies fleet 'value' into consideration before attacking, as well as static defences. AIs have various predetermined programs/personalities/etc. with fixed build orders and different weighting on various things (Fortifier AI values starbases and tactical structures higher, Researcher AI will allocate more resources to labs and teching, etc.). AIs do not have a long term plan, and base all decisions on what they have right now. They will not decide to fast tech to HCs unless their personality has scripted them to do so. They will not decide that the player is too fortified and try to tech to super weapons or something.
Same goes for combat. The AI will not go, "OH SHI-" when they run into two level 6 Marzas. They judge attacking and retreating based entirely on whatever fleet strength values have been programmed into them. They don't take positioning into account. A starbase they jumped their entire fleet into and is firing with all 3 weapons is the same threat value as a starbase on the other side of the well. Cap ship getting focus fired? The AI doesn't care. The only way an AI can ever adapt is if they cheat. Again I don't know to what degree Sins does this, but some RTS AI may be programmed to increase build priority to certain things based on what the player currently has. Spamming carriers? Okay, increase priority to flak.
As for diplomacy, again it's based purely on math and scripted behavior. In Diplomacy, it evens shows you the math the AI is following for how much they like you. Hit X relation points, and they offer a treaty. Fall below a certain threshold, and they break it. They will not bribe you into peace while secretly amassing a fleet on your border. They will not suddenly break a peace treaty for no reason, unless of course scripted to do so based on their personality file.
Anyway, I hope this is what you were looking for and not a boring wall of text.
