Chatting between players, how much is "normal"?
Given the huge variety in the way games are handled here, I don't think there is a 'normal', to speak of. Even within games, such things (OOC discussion to clarify IC actions) is sporadic, when it happens at all...and it all depends on the players involved. I'm in a game where character actions get discussed (sometimes at length) because the players in the game have VERY different approaches to their characters and will sometimes call another player out if they think something's not kosher. Other games I'm in, there's only occasional OOC planning, because the players all seem to click pretty well, and once we settle on an overall approach, everyone is willing to just roll with whatever comes up and discuss fine details as character dialogue, rather than hashing over everything OOC (and, really, some degree of confusion is realistic when you've got characters in situations where the environment can be extremely unpredictable.)
The same holds true for OOC discussion, player to player, about stuff beyond the game. Some games, we have great discussions, and my fellow players were a massive moral support when I had to have a molar taken out in a very long and painful extraction, and spent half a week at home on painkillers. Other games? Other than the occasional post about being slow to respond for a while, or out of town, there's not much OOC discussion at all.
So, yeah...you can encourage it (one GM I play under even has separate threads for OOC chat and OOC planning)...but if the players opt not to use it, there's not much you can do, really.