Does AI cheat in terms of galactic resources?

Technically, yes. The AI knows where the resources are placed. Practically, it's not that much of a cheat, because the AI is also programmed not to go aggressively after those resources. The AI also "wastes" moves for scouting that it does't really need to do.

So, it's a compromise. An AI that doesn't know the map would preferable (one of the reasons why I like Civilization IV so much, the AI there doesn't know any part of the map and actually does its own exploration). But it's also difficult to get AI exploration right, and the respective algorithms tend to hog resources. GalCiv tries to remain efficient by giving the AI some map knowledge, but also tries to balance this cheat by not letting the AI exploit it massively.

Ok - good to know. In future games I will turn out a lot cheap scouts and sweep the areas methodically (hate the time it takes so often ignore it at beginning)

Minor civs are the worst at this. I've gotten into the habit of following their constructors with one of my own that's slightly faster. I don't NEED to scout - just beat them to the resource once I can see it!

I use spies on neighboring civs to get low espionage ability. Then I can see where they are going and beat them there.

The AI's homing in on planets across the map is the most irritating part. I have to spend countless turns as a colony ship goes to a star with zero habitable planets, the AI doesn't.

Sure, spying works, but it's expensive and you would have to build to build a constructor/colony ship anyway...

Besides, that option isn't available for minors   

The AI is *required* to scout any planets before colonizing them at any levels below Genius (at which point it has some chance to "guess", IIRC).