II'm not sure I follow your logic.
In example one, I assume you are taking issue with the "moves adjacent" trigger, maintaining that a reaction can't trigger unless the PC knows its conditions have been met. A not-unreasonable position (but not necessarily one I agree with - although I do agree that not only would the PC have the -5 penalty, they'd need to correctly guess which square to attack).
Simple. The first and foremost advantage of hidden is that your enemies have no awareness of your location or your movement. This advantage does not go away until -after- the action that broke stealth. This means that the character with the readied action never gets to trigger his readied action, because no movement occured that he was aware of.
In example two, why do you maintain that the PC can shoot the goblin? If we have established that the goblin remains hidden until after the end of its move action, and that one of the benefits of being hidden is that enemies are unaware of your position, how do you maintain that the PC knows when the goblin "appears"?
The goblin appears when it loses the invisibility garnered from being hidden. It loses this invisbility after the end of the action in which it breaks stealth.
It's REALLY simple: Appearing is what happens when it loses the benefits of stealth. It cannot simultaneously benefit from stealth and not have the benefits of stealth. Having the benefits of being hidden is a binary state.
Draco, how can one "tell" where you're about to teleport? Teleporting itself could be ruled to give a +20 circumstance bonus to Bluff for the purposes of gaining CA against one enemy. (since it's an encounter power anyway).
Assuming the teleporting character is not hidden, then its enemies are fully aware of its movement and location at all time. The rules do not make an exception for teleportation. Therefore teleportation follows the exact same rules of awareness as every other form of movement in the game. Not to mention, teleportation isn't even all that uncommon--combatants would expect it unless they've never heard of 'eladrin.' And eladrin are not an uncommon race in most worlds.
Moreover... where is it written that teleportation is some invisible thing that circumvents rules of stealth and chicanary? Where is it written that it is inherently silent, and has no visual effects? Where is it described to be different than other effects, and therefore should receive special treatment?
Anyway, our DM gives combat advantage to the rogue for TPing, since while he's outside of reality, even for a split second, he gains complete and total concealment and thus when he reappears it reduces the rules problem to the same one as charging from out of the shadows.
At the end of the teleporting action he is not in total concealment, and therefore cannot make his stealth check to become hidden. Without the stealth check to become hidden, he does not gain the benefits of being hidden. Even if he did, he has also lost the benefits of being hidden after the action in which he teleports.
