Also look at Lyons financial, they will do an execute only AVC with 98% allocation I think. But if you're not comfortable in answering the questions I would advise you get professional advice from somewhere. It's not only Cornmarket who can advise on public sector arrangements so shop around.
Is the Cornmarket 100% allocation after the €100 fee? If you contribute circa €200 per month or €2,400 for the year, then the €100 fee works out around 4.16%. I cannot make out if any other charges are taken and you'd want to be sure of that.