You're welcome in advance.
si jose, you use the Retime node for all of that. This is what you do:
1) Change individual "clips" framerate independent from the project framerate (AE: Interpret Footage)
Example1: read in a 600 frame 30fps clip into a 24fps project and write it out, converting the 30fps to 24fps. To do this, you make
read -> retime -> write
set the retime speed to 1.25 (30/24).
then you wil get the 600 frames squashed into 480 frames. It is still 20 seconds long.
2) Apply time remapping and / or stretching-shrinking effects to a clip (AE: Time Remap)
* stretch the clip = slow motion. Take the same setup but change the project frame range to 750 and the project fps to 30. Make the speed 0.8 (600/750). Now the clip is 25 seconds long.
* shrink the clip = fast forward. That is the same as Example1 but with the project fps at 30. The 480 frames will come out as being 16 seconds.
3) The ability to keyframe individual images from the clip to create holds on specific points in the animation (i.e. Hold the first frame for an X amount of frames, and then continue with the clips interpreted speed.
Example3: Set the retime Speed to zero on the first frame and right click on the Speed field and choose Set Key. It goes blue. Then go to frame 100 or whatever in the timeline and set it back to 1.0. Now you will see your footage hold the first frame for the first 100 frames of the timeline.
4) The ability to keyframe the time remap itself, to have accelerated or decelerated parts within the clip.
Example 4: with the Example3 project go to the Curve Editor and you will see your animated speed curve. You might have to zoom in and out. Also you will have to click the padlock on the bottom of the viewer to lock the curve editor to the viewer. Then you can edit that speed up and down easily. You can add dots and try the right click interpolation option that is good stuff.