To find out what the 1. AD actually has to do, I talked to the second year Francsesca who was working on Cem’s shoot as 1. AD. She gave me some useful tips.
Your two main duties are making the schedule before the shoot and keeping everyone in track with it on set.
If he wants you to sort out the food too, that’s a quite common duty as well. My suggestions are:
when you make the schedule, make sure you go through the shot list with DoP and Director so that you know what needs to change from shot to shot and you can plan a realistic schedule. It also helps you to have a better idea of what’s happening once on set.
Second very important tip is, unless you’re on a chilled set like cem’s where everyone can make coffees when they have time (you need to ask Radu about that) do schedule breaks every few others. The crew gets really tired and doesn’t work very well.
Third tip is: I know Radu doesn’t like mean ADs, ad me neither, so while you go around checking everyone is on schedule also make sure you ask them if they’re all right and offer them a coffee every now and then, so they know you are welcoming and they can come to you if there are problems, which is what they should do.