No, jet fuel is not gasoline, and I'm not aware of a bullet even incendiary causing an explosion for JP4, JP5 ect. Now if it was 100 octane gasoline it would be a different matter. Either way I think it would have had to leak a while and burn to get enough pressure to blow it up and those bullets would leak slowly.
Again, a .223 at 1000 yds isn't going to do it, and most likely neither would a .308, and only two shots at that. I'm thinking those two shots were probably fliers.
This guy had the means, why not use a Barrett .50cal ?
He probably didn’t bring in a Barrett because unlike the other rifles he used, a Barrett isn’t that easy to hide in a suitcase. It’s long, heavy, and very definitely not shaped like a set of golf clubs.
I agree (and independently theorized) that the shots at the tanks were an attempt to blow them as a distraction to cover his escape, and that his cache of Tannerite might have even been intended as an accelerator. I further think that his inability to blow them is what drove him to suicide in a panic when he realized he didn’t have a Plan B. Apparently, the tanks were deliberately targeted; they were the reason he broke out the second window in his suite as it was a better sightline to them from that second window.