1. Can a time series graph show more than one of the features of such graphs.?

Yes, a time series graph can show values which are seasonal, have spikes and ramps, show a long term trend plus long term cyclical variations! The time series you may be asked to comment on would be unlikely to exhibit all of these features.

2. Can a time series graph have curves?

Yes, but usually the points on the graph are joined by straight lines.

3. Does TIME always have to go on the horzontal axes of a time series graph?

Yes, time is always on the horizontal axes.