2 groups sounds like a good idea. Good job
Now not to step on anyone toes or bust anyone's balls, I have done OS10 and OS25 few times myself and it can be done with 2 healers and 2 tanks(OS10 that is) aslong as u have the necessary range and melee dps as far as gear goes yes u need to be on some type of decent gear doesnt really mean u need to be epic out but at least have heroic blues.
But just like Edge recommende, visit Wowheroes so u get an idea where u stand and where to get the next upgrade