For the milky way shots, the "Starry" setting with ISO 80 is not good enough.
Best to try first with manual settings
at ISO 1600, Aperture 3.3 - 4 .
Maybe, the sky is dark enough to try ISO 800, as well.
As for the exposure time on a normal tripod:
that depends on where the object is in the sky and which zoom you are using.
All the way up at the zenith with 25mm you can do 30 seconds without star trailing.
The lower the object is, the shorter the exposure time has to be to avoid trailing.
At 25mm, anything below the zenith looks good at 20 seconds, 25 secs max.
If you use your camera's zoom the exposure time gets even shorter.
You could google the 600 rule.
Or you could just try it out
That's going to be a wonderful experience!