Best way to bake normals for game models?

Hi, all! It's been a long time, I guess. It's a shame that after so much time I'm comming back here just to ask for help, but I guess that's life.  

I've been messing around with game models, trying to become better at making them and I actually learned some new stuff. The thing is that I can't get a good normal map if my life depended on it.  Also, it seems that models that look great in Blender GLSL, don't look so good in Unity, where I'm testing them.

Here's a particular high poly model and both of its low poly game versions:
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Notice how one of the low poly models has additional polyloops around the sharp edges! This one is actually the model that bakes pretty great normals and also looks great in Unity.

My question is can I get great normal map with the lowest poly model (the one that doesn't have additional polyloops)?

Also, what do you think about applying edge split to game models? I've seen many game models that utilise the edge split technique, but none of them have normal maps. This goes both ways - none of the game models I've seen that come with normal maps have split edges.