Should I air-dry or wipe those sterilised bottles? Usually i won't dry them. I'll just shake the water off. Choose not to air dry or wipe as it will be exposed to germs. But my EBM will mix with the water inside. Is it ok?

It is fine to just shake the water off. After all it is sterile water but try not to leave too much excess water inside if not it will dilute the breast milk. Never wipe them dry as it defeats the purpose of sterilising it. Tissue or wipes contains germs from the surrounding.