The only time we usually put it on a line on purpose is after a kickoff for change of possession.  They should not be doing that when a first down is in question. 

The other note you are talking about - the only job of the official under the goal in a 4 man (or 3 man) crew is to tell the referee whether the ball went under or over the goal post.  That is what the official meant when he said he had the over/under.  The referee (back by the kicker) decides whether it went through the uprights or not.

ok, that would make sense on the over/under comment, but when he said it, one of our sideline members said "don't be talking about gambling in front of the kids, that's not cool", and the ref just smiled and shrugged his shoulders then went about his business.  If that is what he meant when he made the comment (that he is determining if it went over the bar or under), he should have clarified what he meant to us when he realized we took his comment the wrong way, then there wouldn't be an issue (plus, i don't even think he was the official under the goal post, but i could be wrong about that).  I'll take your word though and give him the benefit of the doubt that that is what he meant and leave it at that.  Thanks.