I don't know about the second one, but the first one can be inaccurate. I know this, because after I arrive at a planet that I espionaged some time ago,it will often show an enemy character en route to the planet through hyperspace, even after a fleet arrives. The character may have arrived days ago, but their status still shows up as "en route." Failed missions do update data, but I don't know by how much. I know that it only updates true data, though. It'd be sweet if you could produce disinformation when you were playing- convince your enemy that Luke was on some crap planet, then ambush whatever fleet arrives to grab him, right?