Heck no, 5 isnt too young to trade pins. Well I guess it really depends on whether you want to make sure you get the exclusive pins or not. lol
My DH is into pins, and last year he had my daughter trading. She would have been 2 at the time. He had a lot of hidden mickey traders on the lanyards because he was looking for other hidden mickey pins to finish out sets he started. Well, she would trade them for ones on the CMs lanyard that you could get in trading packs. He was good though, he let her do what she wanted.
Adults have to trade from regular lanyards and hip packs the CMs wear.
Children can also trade from those as well as the bright green/teal ones. The green/teal ones are for children-only. Though some cast members really dont care if you ask them.
The pins have to have the disney trademark on the back to be considered tradeable. The rule of thumb is that each person can trade up to 2 pins with a cast member and you shouldnt try to trade a pin with them that they already have on their lanyard or hip pack.
My DH gets his traders from ebay, you can sometimes find someone offering pins -at/around $1 per pin. Much better than buying a trader for the park prices of 7-20 per pin. Only thing to watch for are scrappers, propins, sedesma and the like.
You can wear a lanyard if you want...my hubby has also left his traders in our pack...or he also has a pin trader hat that he likes pretty well. we always are polite and ask the CM if we can look at their pins. We hear a lot of people demanding to see them, and are rude about it. So we try to be cordial. If there isnt anything that catches your eye, you arent required to still trade. We just say thanks and move on to our destination.
Oh...also some CMs play a kind of game by putting a surprise pin on backwards, but you would need to trade for that sight unseen (thus the surprise LOL). I have only done it a few times. usually we get something common (enter the trader pack pins haha) once or twice weve found newer hidden mickeys that way. We figure if we didnt like what we got in the surprise, we can just trade it back to someone else later.
While trading, watch for management members as well. Often they have really good pins.
Hmmm....what other kinds of questions did you have on trading?
Here are some links that my husband has bookmarked on pin trading that you may enjoy as well, or at least find helpful.
News on pins and trading:
http://eventservices.disney.go.com/pintrading/event?id=28460
Great site with a lot of pin info including pics:
http://pinpics.com/