Yes, iPhone X is a water-resistant phone. You can check this video to know more about it. However, we must tell you that Apple does not serve warranty if your phone is extremely damaged by water.
Of course Yes. It has portrait mode which has a reasonable amount of Bokeh. The portrait mode has different lighting options: natural light, studio light, stage light, etc.
Yes, iPhone X does support wireless mirror screening. Check this video to understand how to connect your iPhone X with your TV.