Are you a person that travels very little? When you exit there are two lines. Nothing to Declare and Goods to Declare. Both lanes are patrolled by Customs Officers. What ever lane you exit there still a possibility to have your bags checked even if you went thru nothing to declare.
In Thailand a death has to be reported within 24 hours. So she would have access to your account within 24 hours. Also bear in mind there is a daily limit for withdrawals
You should get a letter from the office that issued your new passport giving the reason why a new passport was issued. Give this letter to Thai immigration and you will have no problems getting new stamps in new passport