It’s hard to argue that you’ve left the atmosphere, when the craft you’re using is supported by it. Hence the Karman Line.

Tereshkova has a much better claim to being the first woman in space.

You can reach the surface of a lake in a craft that floats on water so you should be able to reach the end of the atmosphere in a craft that floats on it.

The surface of a lake is much more well-defined, though, and has high density. You can't "float" on whatever you define as the "surface" of the atmosphere.

Jeanette Piccard and her husband Jean, another high-altitude ballooning pioneer, are also suggested to be ancestors of one Jean-Luc Picard, captain of the USS Enterprise.