The results are summarized as follows:
- x-intercepts of \( g \): \( (6, 0) \) and \( (12, 0) \)
- y-intercept of \( g \): \( (0, -1728) \)
- \( g \) is decreasing on: \( (8, 12) \)
- \( g \) is increasing on: \( (-\infty, 8) \) and \( (12, \infty) \)
Thus, the final answers are:
\[
\boxed{(6, 0), (12, 0)}
\]
\[
\boxed{(0, -1728)}
\]
\[
\boxed{(8, 12)}
\]
\[
\boxed{(-\infty, 8), (12, \infty)}
\]