Since the questions are different, the answers are separated for question 1 and 2
ANSWER:
1) The best question to ask is: "What are the top three sights I should see".
2) Avoid assuming unethical behavior until you clarify what he is asking for in relation to the agreed-upon contract.
Inform the executive that this extra $10,000 wasn't in the original contract.
EXPLANATION:
1) It I very important to know the things expected to happen in the meeting, so that you can prepare ahead for it. Knowing the top three sights will help you prepare ahead for them. This question tends to extract the frequent and most occuring actions the supervisor always encounter during her meetings at Thailand.
2) It is not always right for us to condemn people's actions without the details of such action. Try to understand the details of why the executive wants you to add $10,000 to the cost of the project, so that you won't assume wrongly. And it is always right to specify the $10,000 demanded by the executive as a separate cost from the initial cost of the project, if the money does not directly linked the the initial cost of the project.