Your answers seem to be on the right track. These online homework apps can be picky about the answer they accept, though.
Given , we have derivative
with critical points when ; this happens when or .
We also have <em>second</em> derivative
with (possible) inflection points when .
Intercept
If "intercept" specifically means -intercept, what you have is correct. Setting gives , so the intercept is the point (0, 3).
They could also be expecting the -intercepts, in which case we set and solve for . However, we have
and
so there are no -intercepts to worry about.
Relative minima/maxima
Check the sign of the <em>second</em> derivative at each <em>critical</em> point.
So we have two relative minima at the points (-1, 2) and (1, 2), and a relative maximum at (0, 3).
Inflection points
Simply evaluate at each of the candidate inflection points found earlier.