Great idea. In addition to your free fishing weekend, know that Wisconsin DNR is trying to encourage new fishermen by offering a one day nominal reduced rate available online.
Having taken many groups of novice fisherman, here are some things to consider:
1) Keep things as simple as possible; Leave the baitcasters at home and opt for spincast and spinning tackle. Simple bobbers and Aberdeen hooks with live bait are best. Leeches will get a lot of action as long as the water is above 63 degrees. Bring extra equipment for when (not if) tangles and equipment problems occur. Targeting panfish is often preferred.
2) Your idea of hooking fish and passing the rod is a great idea that we have used. In time they will get the rhythm/ timing of a hook set. Until then, all they want to feel is something pulling back on the line.
3) Prepare for what to do when fish are not biting. We have found that with both kids and adults, a full cooler of food and drinks is a great way to bide time for when fish are not cooperating.
4) Allow them an "out" when they have had enough. The rule on our boat is when one person needs a break/bathroom visit, we all motor back to shore and walk off our sea legs. There is nothing worse than feeling like a "false imprisonment" fishing situation. Personally you might be able to fish 20 hours a day. Be mindful that your guests might not have that sort of attention span for the sport.
5) Encourage sunglasses as a safety mechanism. No, seriously. A bunch of people learning to cast is a recipe for a trip to the ER to remove a hook. Things happen quickly out there.
6) Keep a sense of humor about the whole process. One of my favorite experiences fishing was when we took out some of my wife's roommate's young sons and husband. There was a long lull in the fishing so when the youngest son was digging through the cooler of food I hooked up a banana to his hook and cast it out. The look on his face when he reeled in a tropical fruit he thought was a fish was priceless. A picture of him holding it up like a trophy fish is in the middle of our refrigerator.
Best of luck with your outing, what a great thing for you to do for people.