Now that Tennis is over, I think I understand how this all works finally. I was close, but not quite.
If a character has cover or concealment, they can perform some action with a stealth check. If it succeeds, they perform this action stealthily which means they perform it unseen, unheard, and unnoticed.
HOWEVER, if the character is in just normal concealment or cover, they must MAINTAIN that cover or concealment (i.e. never be in plain site.... without cover or concealment) in order to "appropriately" attempt the action - ruled upon by a DM.
This means that lighting, weather, etc plays a very important part during combat for stealth players.
Total Concealment and Total Cover is similar except that this makes observers not able to see the player at all and in THESE circumstances, you must use the "Target What You Can't See" rules.
What does this mean?
It means a Rogue player staying ducked behind a crate (normal cover) CAN attack stealthily each turn for Combat Advantage and Sneak Attack damage but CANNOT gain Total Concealment or Total Cover bonuses defensively by "stealthily moving" into the same square essentially.
What ever "condition" the player is in when they end their turn (cover, concealment, total cover, total concealment), that is the defensive bonus they get. And when the player is in Total Concealment or Total Cover, they are not seen and this means monsters must make an active perception check to try and figure out their direction or square and then attack a square accordingly.
If a player is behind pillar 1 during combat and in dim light and wants to spend an move action to stealthily move to pillar 2 which is also in dim light, they could do so since they have "concealment". HOWEVER, if there are any creatures that have low-light vision or dark vision, the low light does NOT provide concealment to the player, the player would be in plain site while between pillars and thus the stealth check would fail for THOSE observers. Once this happens, the DM can negotiate communication rules and whether or not creatures with no special vision would be aware of their location or not.
Whether or not this is what is written, intended, or what have you.... this seems to make the most sense to me. It essentially allows stealthers to have combat advantage pretty frequently (which is not a big deal really) but it doesn't grant them defensive bonuses beyond normal terrain or circumstances.
If a player is behind a wall which is several squares long and stealthily moves from 1 end of the wall to the other, thus maintaining cover the entire duration of the movement from observers, then for all intents and purposes.... yes, that player WOULD have total concealment for defensive purposes since observers who failed their perception check do not know where the player is. The same thing would happen if the player had jumped into a small forest of dense foliage, smoke, fog, etc.
The player cannot, however, stand behind a pillar in the middle of a room and expect to stealthily move 1 square away and 1 square back and then have total concealment. Monsters, who are ever watchful during combat, would be aware if someone stepped out from behind cover, and with no other concealment, and moved somewhere. Since the player never did this, whether the stealth check passes or not, the observers still know where the player is.... and no total concealment.
