Hi @loreennaa, communities can filter posts easily by "muting" them. With regards to "cross-posting" into multiple communities, this is something that will be possible with a future version. The goal for the initial protocol was to keep it as simple as possible. This is to prevent launch delays as well as to give us time to collect feedback without being locked into a sub-optimal approach.
RE: Hive Communities: An Interview w/Steemit's Senior Product Engineer