I haven't done it in a while but my recollection is that if you press a "wrong-direction" floor it will just go there after having completed all the previously-selected stops.

not just previously selected but it will wait until there are no stops in the current direction, then switch directions and go in the reverse order

Yeah I wasn't sure what will happen if more people add in stops in the "right" direction afterwards, I don't think I've ever been in that situation, but that makes sense.

The one in my building will allow you to select any floor at any time. it always goes to the last stop in the current direction before reversing as far as i have noticed

I've experienced both kinds of elevators. Some don't let you select a floor that's in the wrong direction, so you can notice you entered the wrong elevator and get back out.