Typically, the door is closed and then the weatherstripping is installed. As was mentioned earlier it is best not to place the door too tightly in the hole. Perhaps this was the consideration when they installed your door.
You may not have to drill them all out. Just do the ones that are buggin you.
What type of weatherstripping is installed? Perhaps you could move that, it may be an easier fix.
Drill out those rivets and replace them with traditional fasteners in the slotted portion of the angle brackets. This will allow you to move the door in or out to reduce the size of those gaps.
All public water systems are required to maintain a minimum disinfection residual throughout the distribution system. Tadpoles would have a difficult time surviving in a chlorinated environment for any significant length of time. You are probably just kidding anyways so thanks for the laugh!