Let's start with a few pies that you can cross off your list if you want to freeze them. Custard, meringue, and cream pies all fit into this category for many reasons, not the least of which is the amount of weeping that occurs. I'm not suggesting that these pies will break into tears at the thought of going into the freezer, but if frozen they will become extremely watery and tend to separate after thawing. Make these pies just before your bake sale.
The good guy pies for freezing are those made with fruit, nuts, mincemeat (maybe the wrong time of year to consider that one), vegetables, or on a different note, quiches.
Now to the question as to whether to bake before freezing. I imagine fruit and nut pies will work really well for your event. Nut pies are best to bake and then freeze, and conversely fruit pies work better when they are put into the freezer before baking. So with your pecan, walnut, pistachio, or any kind of nut pie, make and bake as directed. Cool the pies completely and place on a tray and freeze until firm. Remove them from the freezer and prepare and wrap for freezer storage (see below). To serve frozen nut pies, thaw and serve chilled or at room temperature, or for warm pies, thaw and reheat in a preheated 325-degree oven until warm or until a metal knife feels warm after being inserted into the pie.
As far as fruit pies go, it's not that you can't bake and freeze them, but you'll find freezing them unbaked makes for a better finished product.
