What is the appropriate mechanism for finding administrative support for a conference?
You may want to think about whether you need a full-time administrative assistant for that, or maybe students could take over some of these tasks. It probably depends on the size of the conference also. But I generally found that students are very well willing to take over such tasks, because it allows them a little bit to peek behind the curtains of conference organization.

An important question when engaging students is whether you have funds available to support the conference organization. If yes, then I think it should be easy to find students willing to help for a small salary. Otherwise you would have to rely on volunteering, which may be more difficult.