There are lots of sites and forums that are specific to photographers. The rules on model release forms (and the several variants) are (to me) as arcane as the intellectual property rules.
Is it wise to get a release form from the parents and does it have to be as detailed or formal as a release form for a living model?
Huh? The kids
are living models and they're not legally able to sign the form. Short answer is yes, you should protect yourself with permission forms. The longer answer is that I think it should be the coach's responsibility to do it since they're the ones requesting the pictures and make sure that it happens, so both of you are protected. All it takes is one parent to suddenly decide they didn't like it and you've got potential trouble. Personally, I wouldn't go overboard with it--use something simple that acknowledges the parent's knowledge of and permission for what you're doing, how the images will be used and whether or not you the will retain the images and/or slideshow.
Dick