setting duration for tiffs in sequence

Hi:


I've imported a tiff sequence to AE, 320 pics to be rendered out as a q-time movie. First time I rendered the movie ( imported as comp ) it came out jumpy. Now I'm trying to import files as individual pics and set each frame w cross dissolve, each tiff 2f. My problem: tiffs come in as 20 sec each. All tiffs are selected in timeline. I go to Animation, keyframe assistant, sequence layers. set to 2F but they still remain @ 20 sec.
My comp is set to 20 sec.
Is there a way to set duration to 2 frames for all tiffs at once in the 20 sec comp?

Or : What would be the best compression to render out a less jumpy q-time?
( First time I used no compression )

Tiffs are exported from C4D.

Thanks anyone!