At conventions of more than 1000 people, traffic to the Operations desk to make simple queries will become large enough that the staff can no longer handle the total load. A separate function to intercept questions that can be answered easily helps unburden the Ops staffers, and has the benefit that if the desk staff are given a suitable reference they can be recruited from day volunteers.
The Information Desk should be located in a spot at least as visible as the Ops desk, or no traffic will be diverted. If the info desk reference material is electronic in form, make sure there is suitable power available.
Information to Have
At minimum, the Information Desk should have copies of all con publications.
A template for gathering answers to frequently asked questions: File:Book of Answers.doc