In terms of what the AI is limited to, it's not exactly what you're limited to. In a lot of respects, the AI is
more limited than you in terms of what it is allowed to know, and in a very few respects it's allowed to know slightly more.
Examples:
1. AI guards on adjacent planets aren't allowed to know when you're attacking a planet; they just sit idly by, doing their jobs.
2. The AI has a rough idea of the count and firepower of ships on planets that border its own ships, rather like if they had a basic scout there (which is what you're mentioning).
3. That said, the AI is NOT allowed to know specifically what targets of value are on the planets it is not on, and it has to find out fresh each time it gets more ships sent there. Very much unlike you.
Those are just a few examples, but hopefully that makes sense. That's why I say that what the AI knows is pretty much
equivalent to what you know, but it's definitely not the same type of data or the same mechanisms for gathering them. All in all, though, the AI is a collection of entities, and each one is vastly more limited in what it knows, with the overall AI controllers knowing a bit more but still not as much as a human player would. Hence the flocking and emergent behavior is able to come out, etc.
In terms of cloaked ships:
1. You can see how many there are on the planetary summary sidebar if you have a scout there.
2. Yes.
3. Decloaker works pretty well, or you can do a tachyon warhead if you're really impatient. Or just don't worry about it, if there's only a few of them. However, if it's a planet that was previously held by the AI, then be sure and send your decloaker around to each of the metal/crystal deposits, since the AI is probably at one of those. If not one of those, then they're almost certainly at the wormholes. It's pretty rare that the AI cloaked ships are just out in the middle of nowhere (though it does happen), which is what makes the decloaker easy to use in the majority of cases; just set up a winding path across all the m/c deposits and wormholes and see when something starts shooting at you.