I'd suggest splitting off the refinement to another feat so it's clearer (one feat to learn the spells, one feat to add refinement to a known spell). It would be like how it is now, but you'd have two different feats instead of the same feat twice doing different things.
So epic spells are at will, then?
Also, what about the save DC? There's no generalized formula, although every spell with a save seems to be 10 + 1/2 CL + primary casting score. However, since epic spells aren't tied to class, which primary casting score? Both for multiclass characters, and for characters in classes that use different scores for different spellcasting aspects (such as Favored Soul).
Edit: Obscure - Acting Below Notice says "your spellcasting ability score", not "your primary spellcasting ability score".