No it doesn't. Everything-stat changes and secondary status afflitions- are removed upon switching. However, if you use the move Baton Pass, the stats and status will be passed on to the next pokemon.
No, unless you use Baton Pass.U-turn and Volt Switch don't activate it, Just baton pass.
No, it loses all stat changes so beware of dragon tail lol
But you can pass the stat boosts with Batton Pass (Move)