A couple questions

I personally thought this was a pretty good movie but I had a couple questions that maybe someone can help me answer. First of all, in the beginning of the movie, they mentioned the Spear of Osiris which, as you all know (if you've seen The Mummy Returns), is the only thing that can kill the Scorpion King. Now, regarding the Spear, what exactly did they say about it? I missed it. Secondly, in the scene where the crowd is sprayed with oil, where does the oil all come from? I mean, I know the jars in the courtyard tipped over and poured oil into the grooves in the ground, but how could that little bit of oil be enough to shower the entire crowd? Maybe I'm reading to much into that, I dunno. And my last question is why did they wanna burn the crowd? I don't understand that. Thank you to anyone who can help me!