This is a repeat question - it has already been answered.
The taking out of the car seats is Your Call - you decide.
Where the water is getting in is an observational thing - the people here can't see your car.
Somebody has pointed you at the access hole for the aerial - presumably you checked this overnight.
When it's dried out take it to a car wash and look for the dribble.
Incontinance comes with old age - sad but true.
Peccavi
November 2009