Wow. I didn't realize you wrote up all of them! I'll just hit on a few.
The Skill tag feats might actually work well, because in order to get a large benifit from them, you have to invest three or more feats. I suppose three feats for +6 to six skills isn't that crazy. You only get seven feats.
As for Cleave and Great Cleave, I like that you can cleave if you do enough damage. This makes it useful at higher levels. Still, it looks like you don't have anything in there for being able to cleave if you simply kill the opponent with less damage. Also, I'm unsure what "conversion" is. A house rule? Lastly, you might want to put something in Great Cleave preventing a 3rd or later attack from striking an opponent you've already struck.
Toughness might just be simple enough to let it stack like you did. Below level 10, it's weaker than the version I posted. Beyond that, it's stronger, but how much will a difference of 10 HP make per feat spent at level 20? Probably not much.
I still have work to do on my own feat rewrites, but I might have to borrow some ideas. I'm assuing you don't mind becuase you posted them here?
Feel free to use them. They weren't doing any good sitting on my hard drive anyway!
The [Skill] feats were, quite honestly, the only way I could even remotely justify them even being there. I had considered wholesale deletion, but as I mentioned above, deletion is not fixing.
Ignore references to 'conversion' here - it is a houserule, and a very poor one. Add a clause about opponents dropping when dealt below the threshold for cleave, and remove the Great Cleave 'backspin' problem. Never noticed them before, sadly...
As far as Toughness is concerned, I went for simplicity. It is kinda weak, I admit, but I'm sure we can do something to shore up earlier levels - what about adding your Con mod to the hp that you gain off it?