The answers to the sub-questions are:
- (a) The function is not differentiable at \( x = 7 \).
- (b) The values of the derivatives are:
- \( g'(0) = -1 \)
- \( g'(1) = -1 \)
- \( g'(8) = 1 \)
- \( g'(10) = 1 \)
Thus, the final answers are:
\[
\boxed{x = 7}
\]
\[
\boxed{g'(0) = -1}
\]
\[
\boxed{g'(1) = -1}
\]
\[
\boxed{g'(8) = 1}
\]
\[
\boxed{g'(10) = 1}
\]