it sounds like you are using the ipb caching system to pull the variable rather than pulling it from the db for the poster. look around in the topic_linear.php code and you will find a variable that is the posters ID. Then you can construct a sql query to pull that variable from the member_extra table or wherever you stored it.
This isnt an issue, but as general programming etiquete you should have 0 being no and 1 being yes. This is a reference to binary as 1 is on and 0 is off. Its just how its always done, but dont change it if you are used to -1 as off and 0 as on. It just struck me as a bit odd. But programming is more about you understanding the concepts so if you like it that way, then leave it

. having it with 0 as off and 1 as on will enable you to do something like this:
CODE
$x = 0;
if($x)
{
//this code wont be executed because $x is 0 :D
}
but then you could just as easily do something like this:
CODE
$x = -1;
if($x == 0)
{
//this code wont be executed because $x is not equal to 0 :D
}