I have some good news .. I was able to get an interim EAD eventhough I did not meet the 90 day criteria ( actually it was about 45 days ) . All I had to do was to get a letter from my employer stating that I won;t be able to continue working without a valid EAD and the lady at the seattle office was nice enough to give me an interim EAD the same day. I took an appointment "to speak to an immigration officer" not for the "interim EAD".
So you can try talking to your local USCIS office .. if they are in a good mood you may get an interim EAD..
As for continued employment, I was not able to find any info which confirms that you can continue working while EAD application is pending..