Harry Potter and exercise

So I saw Harry Potter 3 this weekend. Liked it quite a bit. If you hadn't read the book, you might be a bit confused though.

Question about those of you who exercise: Any tips on how to keep good form during crunches? I was working on my abs last night and I think I accidentally used some neck muscles. It's weird, 'cause it's the front neck muscles that hurt. I think I might have been keeping my chin too close to my chest. The video recommends that you imagine an apple/orange between your chin and chest. I may actually have to resort to that.

So I finally got my pants on Friday. Of course, they're a bit tighter than I like or usually wear pants. They're low waist, which I'm not used to wearing. I guess they just hit me in a different area. I only really notice the stomach tightness when I sit down. The one pair of capris is really tight when I sit, but it's got that weird clasp thing instead of a button, so it closes a bit further in. Hence all the work on the abs. Tips would be good please.