If a school say admits 180 pupils and is full and 2 appeals are upheld and the number increased to 182 is it correct that places will then not be offered to people on the waiting list until the numbers are back below 180.
That is correct. Nothing can be offered from the waiting list until the number drops to 179.
If this is correct is it justified to question the panel on the movement in the waiting list that normally occurs between when the appeals are decided and the start of term?
You can't question the panel, but I don't think it's unreasonable to ask the authority's representative about pupil movement.
The schools arguement is bascically that it is full and that to admit extra pupils would prejudice those pupils who already have places. Given that the appeals upheld from this school are only 1 or 2 in past years my feeling is that those pupils getting in on appeal are only replacing those that would ordinarily have got in from the waiting list and would not lead to excess numbers.
Panels are unlikely to get involved in anything to do with the waiting list, unless there's been maladministration, or to speculate about future pupil movement. The issues for them are whether the admission number has been reached, whether the admission of an additional pupil will cause prejudice, and whether the appellant's reasons for wanting a place outweigh the prejudice to the school.
A panel should not be told where you are on the waiting list:
When hearing appeals, panels must not take account of where the admission authority has placed a child on the waiting list, or of the fact that appeals have not been made in respect of other children on the waiting list.
Also what happens if I ask a question of the schools representative in the appeal such as the above and they do not know the answer?
The Code states:
The presenting officer will need to be prepared to answer detailed questions about the case being heard, the school (including its admission arrangements) and local coordinated admission arrangements
I think it would depend on how significant the missing information is. You could try asking the panel for an adjournment so that the representative can come back with an answer. (This might entail a short break for a telephone call to be made - or it might mean postponing the hearing to a later date.)