I actually did not see that the latest meeting was today or I would have tried to come, although actually I was at work. Do these often happen during the weekdays, or are they also on weekends?

The meetups at Caffe Medici are every Saturday at 1:30 pm. We have a group meal on Wednesday evenings, with details announced (and food orders coordinated) on the list.

Is there some sort of email notification or something that notifies of Austin meetings?

The list has day-of announcements of the Wednesday group dinners, and discussions of any of the irregular things that we do. For example, we might go see The Martian together tomorrow. When there's an established plan for the meetup, I've started announcing those by email but that's inconsistent.