As a newbie working on automotive shows, I have a question...

Take a look at www.riceboytv.com and watch any of the clips.

Are they using Premiere to edit clips, then going into After Effects with the draft of the movie to add the special effects, like shaking cameras, old film effects, etc?

Either way, my question is as follows:

To add effects to finished 8 minute movie of about 90MB fully rendered, is it possible to import the 90MB movie and add the effects to that, or do I just import the clips to which I want to add effects?

Nothing unusual about the videos, as far as I can see. You can use either approach. If you have Premiere and AE with Dynamic Link you edit the whole sequence in Premiere, setting the cuts, the pace, deciding the effects. You can then import the PPro project directly in After Effects and add all the transitions/effects. Or you can render to uncompressed and load the clip in AE but you loose the structure of the footage.