I went on one yesterday that had about 35 participating riders moving from house to house across town to see different music shows and while it was fun, it wasn't very well organized. There were riders of all skill levels but no separation so we'd always get a "slow down" yell when climbing a hill or traveling on main roads. The strategy of the leaders to keep anyone from being hit was to ride down the crosswalks and block incoming traffic from crossing an intersection, even if the traffic lights were in their favor. And because the group couldn't keep together, there were a lot of confused people.

I want to organize a casual ride down to a local state park in a few weeks for those who like to ride longer distances than downtown Tallahassee. The ride will be about 21 miles long, with most of the distance on a multi-use trail, with 5 road crossings in town and then a long peaceful ride all the way to the destination(Map here: http://www.mapmyrun.com/route/us/fl/...28435233776108). I'd like to leave in the morning so that people have time to eat, swim, take boat tours, hike, and whatever else they might like to do there and leave in the late afternoon so that we can get back to the starting point without any need of headlights. I have talked to a few people who have emphasized the need for a A and B group so that fast riders don't have an unpleasant ride and slower guys don't feel so left out. I need some advice before I start telling people that this is going to happen though.

1.) How do I control 20-30 cyclists going through an intersection? Or riding on a main road? Most people who ride in Tallahassee don't go more than from home to class. On the ride I went on, conversation and simple showing off had people riding all over the road and being nuisances. I don't want to play daddy but I want to let everyone know that some actions are not appropriate for a safe ride and let them know what we'll be doing at each intersection beforehand so that there's no confusion.
2.) It's still storm season so our weather is really unpredictable sometimes. What happens at a cycling event when the sky is throwing out rain, thunder and lightning? Is the event a bust? Do we just wait for the storm to break or does the show still go on? What if we find out that we'll have serious storms throughout that week?
3.) Are there any precautions to take in case of injury, aside of a biker boo-boo kit?

Please throw in any useful advice that you have, I'm excited about this but I don't want to start making flyers and e-mailing facebookers till I'm confident about taking a group of people I don't know out on an epic ride.