I find a graph of the function to be helpful. Desmos.com can also do function evaluation and derivatives and integrals.
1. The average velocity is given by (v(8) -v(0))/(8 - 0) = -1 meter/second.
2. v(5) = -2 meters/second. The speed is the magnitude of this, 2 meters/second.
3. v(t) > 0 on the intervals [0, 3) and (6, 8] seconds.
4a) velocity is increasing on the interval (4.5, 8] seconds.
4b) velocity is decreasing on the interval [0, 4.5) seconds.
5. The integral of speed over the interval is 35 2/3 meters. (The net distance traveled is shorter, because some of the distance was in the reverse direction.)
