If they have too many entries they will close on the ballot. They then normally say if they are balloting, sometimes v quickly othertimes it takes a few days. if they have enought entries, but not too many then they will close on ballot date and not take anymore....
Yes, you can enter after the ballot date. Just monitor the bdwp site to see if the class you are wanting to enter is still open after the ballot date. They are normally pretty quick putting up the list of who has been balloted, again keep looking at bdwp.