This was my air filter I replaced just a couple weeks ago. The car had the snorkel attached. I also vacuumed some leaves and other debri out of the airbox, the filter did it's job well. That being said, things will get in your intake regardless, just make sure you check it every so often and replace the air filter every year or so. Its a small expense to keep good airflow. I replace my airfilter in my home air purifier every 3 months and it costs the same as the filter in my Boxster so I don't mind do the car the courtesy every 6 months to a year if I have to.
As for the water, avoid the car wash and you with be fine.