* Since when does the Rowbotham Institute have dozens of soldiers ready to fight the U. S. military at its beck and call?
A) Nobody said it was the US military
B) 'Soldier' was the scientists and engineers working there who were armed to defend against attack. it does say that

* For that matter, why does it have all of this stuff? The companies who sponsor it wanted to set a trap, you said. A trap for who? Random people called to be explorers? Tom Bishop himself? If they really wanted Tom dead, they wouldn't need to waste all the money. Your conspiracy seems to have ties to the military, so they could send a professional to kill Tom and make it look like an accident.
Why would I spoil the mystery?
* If Diego and Z are assassins for the conspiracy, then why do they attract so much attention by being so obnoxious? That's the exact opposite of what they should be doing. A real professional would just be sitting quietly and keeping to themselves.
Exactly. People would expect the pro to be calm and discreet. Who suspects the obnoxious sexist twat as an international undercover spy?