Unsolved Mysteries Of Godzilla 2014 (Spoilers!!!)

Hello! Seeing this movie 4 times already, I have a couple of mysteries that you guys can possibly answer regarding the new Godzilla of course. Here is a list of mysteries I have regarding the film

1. What was the skeleton in the beggining of the film?

       I heard many people say it is Shinomura, from the Godzilla: Awakening book, but there is 2 problems. First, Shinomura was a creature that was made up of many "cells" that act as one. So, it is impossible that a creature like Shinomura will leave any skeletal remains. Second, Shinomura was killed by a nuclear blast (I think, I haven't read the book since May 9th). Shinomura got incinerated.

2. The mysterious giant dirt trail leading up to the ocean

      At first, people were speculating that what caused the trail was the multi-armed centipede creature or Godzilla's tail, all of which have been proven wrong. It can't be the centipede creature because.... it is not in the film itself. It can't be Godzilla's tail because there would've been footprints. What is it?

3. The Stadium Scene

     Ok, instead of a mystery at the beggining of the film, this one is at the end of the movie. Anyways, remember that touching scene with Ford and his son waiting for Elle and she eventually comes and hugs and/or kisses Sam and Ford? If so, how did Sam and Elle get to the stadium. If you remember, Sam was in a school bus and made it across the Golden Gate Bridge before Godzilla destroyed it in half. If the stadium was across the Golden Gate Bridge, then how did Elle get to the bridge if the bridge is sliced in half? If it is near the area where Godzilla battled the Muto's (which I think it was near where Godzilla and the Mutos were at), how did Sam get there if Sam was across the Golden Gate Birdge and the bridge is sliced in half

4. The Mega-ton Explosion

      Remember the scene with the Mega-ton bomb on the boat where Ford is at? Well, when Ford was picked up from the helicopter, it said 13 minutes, ___ seconds and __ miliseconds. What happened with the bomb? Why is there still people alive near/on San Francisco? The Admiral showed them a map of how much destruction a Mega-ton bomb can do and it appeared that it can decimate San Francisco and possibly destroy California. What happened with the explosion? It definately passed more than 13 minutes when Godzilla left San Fran. There was even some building still standing up.

5. Serizawa, Vivenne and "Monarch" Location

      Where was located the place where Admiral Stenz, Serizawa and Vivenne at? At first, it seemed that they were near the Janjira facilty where the male Muto went loose. In another scene (the last scene where Godzilla was "sleeping" at San Francico), we see Serizawa and Vivenne in San Francisco. How whas that possible? How did they end up being at Japan, all the way to San Francisco in a matter of 3 days in a boat?!

    Anyways, that is about it. Sorry for the long read. Before I say goodbye, here is a picture of the 2 Mutos: