Right, longer would be Bulb shutter setting (is as long as you hold it), but you would not need that for the moon.
Two reasons... the earth will rotate enough in 30 seconds to blur the image (unless you have a tracking mount).
But mostly because the moon is illuminated by direct sunlight, and exposures closer to normal daylight would be expected.
And three, automation makes it be very difficult. Manual exposure and manual focus is much easier on the moon.
Focus will be difficult, but much easier in Live View, AFTER you zoom the viewfinder in far to see it very large (so you can manual focus).
For a full moon, maybe start in ballpark around f/8 1/100 second, ISO 100 (manual mode), and experiment, but don't overexpose it.
See
photographing the moon - Google Search