Stormborn
Explorer
I love the IK books, but found many of the special mechanics very very frustrating in play. For one thing, the Gun Mage could have been handled with a few feats, IMO, made available for spontaneous casters, at low levels, as written, it just doesn't really work out. The Witchfire Trilogy, or at least the first 2 I have played through, are poorly done (a 3.5 version is supposed to be in the works but don't know if it will fix actual story issues).
Keep in mind that IK has technically been around for a long time. The Lock and Load guide came out years ago, but the rest has been somewhat lacking. It has the feel of a long running homebrew, where things have been tweaked and retweaked w/o a serious conscious effort to reconcile them to the balance of the sytem as a whole.
However, as has everyone else, I strongly recommend Monsternomicon.
As to the original poster's question: go elsewhere for your steampunk rules, good suggestions have already been made. I would honestly consider Eberron from what you described over IK, with some tweeks of course.
Keep in mind that IK has technically been around for a long time. The Lock and Load guide came out years ago, but the rest has been somewhat lacking. It has the feel of a long running homebrew, where things have been tweaked and retweaked w/o a serious conscious effort to reconcile them to the balance of the sytem as a whole.
However, as has everyone else, I strongly recommend Monsternomicon.
As to the original poster's question: go elsewhere for your steampunk rules, good suggestions have already been made. I would honestly consider Eberron from what you described over IK, with some tweeks of course.