The high-gain antenna on the MALP is pointed at the sky, making it useless for communicating with Earth. It should be pointed at the Stargate.
Any second or later generation star, i.e. one that did not form immediately after the Big Bang, contains varying traces of heavy elements stemming from the Supernova remnants from which they formed. Though they may only make up very small percentages, in absolute terms, they amount to millions and millions of tons because stars are so massive. No amount of plutonium so small its effects could be offset by a rocket payload of some other element could ever make the slightest bit of difference to a star, not even the smallest one.
Carter was talking about finding a stable, super-heavy element with an atomic weight above 200 in order to bind with the plutonium atoms in the star. Plutonium has an atomic weight of 244, so Carter should have specified that the element they need would have to have an atomic weight above 244, as there are a number of elements on Earth that fit the description of having a weight greater than 200, like lead, for example. It's elements with an atomic weight above 244 that are very rare.
At 39 minutes, Carter was using the computer to dial the gate. But the screen showed "User Sgt. A. Wilson".
While Jack is speaking to the Asguard, they speak of the treaty and how it would be a violation to interfere with a pending natural disaster. The disaster is man made, not natural. Therefor, it would not be a violation.