It will depend on crowds (in line for Fantasmic) and the time of the show, which appears to be 8:00 each night. I would check in a bit early. We always have to wait to be seated, but service is usually quick. And, there is a ton of seating for fantasmic...sometimes coming in later gives you a few more options....I would think you could easily be there by 7:30 or soon there after.
Can't answer the other question. During the summer, the show was 3 times a day, all in the afternoon, but based on the calendar, it sure looks like only once now....and you won't make the 5 at Sci Fi...the show was almost an hour, but "exit" time....if you know what I mean.