Try your local shop for the missing plastic piece that holds your chainguard in place. All of those newer plastic chainguards come with very similar hardware.
As said before, those 'nails' get crimped onto the ends of your brake cables (otherwise they unwind).
The s-curve might be to clip your brake cables together, for neatness' sake.
Its hard to judge your chain from here, but its probably ok as long as your cranks and cog/lockring are tight. You DID tighten your cog and locking, right?