i don't care about the G1 issue, but i think soundwave should not have lips. supposedly he has his G1 voice, so there wouldn't really need to be lips, just speakers...i like the idea of a faceplate/speaker thing.
Judging by what we've seen on the toy so far, it would appear that Soundwave has a mouth similar to what Megatron and Barricade had in the first film. Now, Soundwave's Protoform toy does not have a mask. I doubt that Soundwave will end up with a faceplate in the movie because if he did, Hasbro would most likely have used the faceplate on the toy like they did for Optimus Prime in the first movie toy-line - possibly to pay homage to the G1 character design. Whether he gets a face-plate for his earth mode toy is another question... So it seems that at this stage Soundwave has no "lips" but he does not appear to have a faceplate either.