It can happen to a visiting pitcher as well, it's just that the win would not be a walk-off. There have been many times when a pitcher loses a lead in a save situation in the bottom of the 8th but gets the win when his team scores in the top of the ninth.
It's not automatic that a postponement today would be played tomorrow but both teams have tomorrow off so I would guess that's what they would want to do.
My weather app says 70% chance of rain today and 90% tonight. Both teams have an off day tomorrow so I'd guess they'll play tomorrow afternoon if they can't go tonight. Shame for me (and I'm sure for a lot of us here) because I wouldn't be able to watch.
I see they have assigned Berrios jersey # 17. I like it that they didn't give him, say, 68 or something. A low number says to me that they're serious about having him around for a good long time.