Q's about movies that have been on cable lately

[VBM]

Been spending a lot of time watching/rewatching movies while on paternity leave. I got like a ton of questions about a few of them:

Kill Bill Vol. 2
1. Why does the Bride cry on the floor at the end?
2. Bud shoots the Bride with a "double dose of rock salt." Is it literally rock salt? Can you do that? wouldn't 2 regular shotgun shells just have killed her?

Collateral
1. The wolf crossing the street; what is the symbolic significance of it? Is this a scene you might actually see in L.A. in the middle of the night? Seems a little implausible...

Magnolia
1. The frogs that fall out of the sky. I never understood this. It seemed gimmicky and weird.
2. Everyone singing. I never understood this. It seemed gimmicky and weird.
3. Phillip Seymour Hoffman. I think this is like the only movie where he isn't playing a wretched person?