Question: What is the name of the song played when the boat leaves Lagos, and is cruising up the Niger River?
Question: What exactly is Kazim attempting to gain/accomplish by killing the doctors?
Answer: So they will not discover the poisonining that is going on.
Question: In the scene where the three main characters are in the Texas and are being bombarded , Dirk claims that the plates are 2 feet thick. They then discover the use of armor-piercing shells. Does he mean 2 inches? I believe the boat would sink if they were indeed 2 feet thick.
Answer: While Dirk seems to be exaggerating slightly, there were certainly many classes of WWI and WWII battleships that had armor in excess of 18" thick in places. They floated just fine - in fact, they were notoriously difficult to sink.
Answer: "Here We Go!" by Clint Mansell. It is on the Sahara soundtrack.