Question

Obvious strategy with Shinpora.

Answer 1

It may eliminate stat changes so it would allow confusion and eliminate the attack gain.

Note: it says "may eliminate" so sometimes it will allow stat changes.

Answer 2

Not exactly. It halves the chance of a status move working. I take that to mean Swagger now has only 45% chance of working instead of 90%. When it works, it will do what it normally does - raise Attack two stages and make them confused.