Does saving after completing the Suicide Mission count?
Solution 1:
All of the Mass Effect 2 DLC is playable after the Suicide Mission. Some of it can be played before, but it can all be played after.
Decisions made during DLC missions played after the Suicide Mission are imported into Mass Effect 3. I played all of the post-release Mass Effect 2 DLC after finishing the Suicide Mission (Kasumi, Overlord, Lair of the Shadow Broker, and Arrival) and imported my Mass Effect 2 save into Mass Effect 3. My Mass Effect 3 play through did honor the decisions I made during the Mass Effect 2 DLC missions.