Timecode

In After Effects the timecode for your current footage will always be shown below the currently displayed monitor.

Adjusting Clip Speed

There are three main paths to go about adjusting speed within After Effects. The composition bin, the Layer Menu, or via an added effect.

Reversing Time

The simplest form of reversing time altogeher is using the time reverse layer command, which can be found within the dropdown menu...

"Layer > Time > Time Reverse Layer"

Keep in mind; you'll need to make sure to select the layer within the composition timeline first. It will need to be done for each clip within the composition. And there won't be an immediate notification or visible indicator that it has worked. Play to preview.

Warping Time

Warping time within After Effects is done primarily through adding layer effects. For instance if you want to vary the speed of the clip to make it go at slower or faster speeds at user-defined positions then you can enable time warping through the menu; "Layer > Time > Enable Time Remapping".

This will create a "Time Remap" entry within your clip properties in the Timeline window. Toggle on the "Enable this property in the graph editor set" button (next to the keyframe stopwatch) to see and edit via a bezier path the time scaling whie the clip is playing. You can of course see the graph editor by clicking on the icon for it at the top of the Timeline interface.