+1. The Ruger .22s are cheap, parts are easy to find, and you can customize the crap out of them. Rugers .22s are like Miatas, as long as you have the shell of the car (or receiver for the .22), you can buy all aftermarket parts to put it together. A .22 will also be a lot more manageable if you have someone with smaller hands or little arm strength. Ammunition is also significantly cheaper.Would it be completely out of line to suggest the Ruger Mk. III or Mk. IV? I remember it's what I learned to shoot on. Reliable, fun to shoot, and has all the basic parts of a pistol if you wanted to explain safety and firearm operation to a total novice.
EDIT: pretty sure that's exactly what you're planning on, anyway.
Find what is popular in your area for shooting sports (i.e. USPSA, IPSC, etc), and attend a couple of matches as a spectator. Talk with some of the competitors and get a feel for the nuances of the rule books, etc.
Now, for the administrative side:
Is it a collegiate or a high school team?
If it will be high school team, you'll have to get parent waivers since all the shooters will be under 18, plus have to figure out a way to purchase the pistols (dealers can't sell a handgun to an individual under 21).
Either way, do a search for schools (be it college or high school) in your state that have a pistol marksmanship or shooting team, and see if you can get a copy of their by-laws, and possibly speak with someone for advice and experience in getting it set up with your school. You'll also want to contact 4H and/or FFA clubs, as some will have a marksmanship or shooting as well. You'll also be able to get their take on what the various leagues and matches offer.
If you've already gotten all that figured out and looking for practical tips, I'll be more than happy to help you out on that end as well.