PCA9306: Questions about internal switch

Part Number:PCA9306

Dear Team,

I have two questions about PCA9306 as below.

1. I want to know is SW a pure Mosfet in PCA9306? Is there any other control logic in PCA9306 (like one-shot circuit in TCA9406) ?

2. Patrick showed below figure and illustrated the concept of the high bit pass from the host to the slave in another E2E thread. 

    But I have a question that will it has reverse current from 3.3V to 1.8V? Is our switch Hi-Z also when high bit pass?

Thank you.