This is my stab at fixing it,based on the last playtest recommendations.I did not address the special sensory abilities questions.
STEALTH(REVISED)
(Dex; Armor Check Penalty)
A successful stealth check grants the 'Hidden' Condition.
Hidden: You are difficult to detect but you not invisible. A hidden creature gains a +2 bonus on attack rolls against sighted opponents, and ignores its opponent's Dexterity bonus to AC . You do not have line of sight to a creature that is hidden from you.Hidden creatures benefit from total cover if affected by an indirect attack;and may not be targeted directly.
Taking any action that would cancel Invisibility also cancels the hidden condition once the action is performed.
Deliberately making noise by speaking,casting(V),attacking inanimate objects etc.. forces a new stealth check at -10.
Moving within 5' of a creature from whom you are hidden allows them to make an active perception roll to detect you.
Action: Usually making a Stealth check is not an action. Using Stealth is part of the action you are taking.
Check: The difficulty for the successful performance of stealth is equal to the Awareness score (10+perception) of those from whom you wish to hide.The DC is increased by +2 for every additional dupe beyond the first.
Usually a Stealth check is made at the start of an action,and only when you have some kind of cover/concealment.
You may also spend a swift action to stay immobile and make a Stealth check if you have cover/concealment.
You can move up to half your speed and use Stealth at no penalty. When moving at a speed greater than half your speed and up to your normal speed, you take a –5 penalty.
When you make your Stealth check, those creatures whose awareness you have overcome treat you as hidden until the start of your next action or until the end of your turn if you do not end your turn with cover or concealment.
You are not hidden from creatures that are observing you.
Searching: A creature who is aware of the presence of a hidden enemy may make an active perception roll as a movement.
Sniping: If you already are hidden to a target and you are at least 10 feet away from that target, as a standard action, you can make one ranged attack against that target and immediately make a new Stealth check to stay hidden. You take a –20 penalty on your Stealth check when attempting to snipe.
Dispatching: A character with the hidden condition who kills or incapacitates/mutes a target in melee combat with a single strike,may attempt to remain hidden from any remaining observers by making a new stealth check at -10. using a Garrotte reduces the penalty to -5.
Creating a Diversion to Hide: You can use Bluff to allow you to use Stealth. If you do not have cover or concealment, as a swift action, you can attempt a Feint check. If you are successful, you gain concealment for a single movement action.If you succeed at your stealth roll and have cover/concealment once the your turn is complete you are Hidden.
Improved feint grants the hidden condition immediately but it is lost if you attack or end your turn without cover/concealment.
Greater feint allows you to snipe or dispatch in the open while hidden,but it is still lost at the end of the turn if you do not have cover/concealment.