1. Can a time series graph have curves?
Yes, but usually the points on the graph are joined by straight lines.
2. Does TIME always have to go on the horzontal axes of a time series graph?
Yes, time is always on the horizontal axes.
3. Is it best to use moving means or moving medians when smoothing a curve?
A moving mean of order 5 uses ALL 5 of the values so will be effected by any extremely high or low values, whereas a moving median of order 5 is not effected by extreme values.