Excedrin contains acetaminophen, caffeine, and aspirin. All three of these will not interact with Atenolol. HOWEVER, taking two Excedrin is the same as drinking two cups of coffee back to back....
Yes, this is OK. Diclofenac is a pain medicine. It's not going to interfere with the diet pills. Remember that it's hard on the stomach though. Have some (healthy) food before you take it!
Sudafed does make your heart race and increase your blood pressure. If you are good and stable and getting good readings with your atenolol, then I'd say go ahead and try it. If you are not stable,...