Re: Extremis:
1. One of the bad dudes looks very much like the antagonist from the comic, even gets killed somewhat similarly (blasted through the chest). Doesn't get decapitated though, which is too bad.
2. The Extremis serum is taken from the comic, albeit the transformation is significantly toned down.
3. It's mentioned in the comic Stark had a surgery to remove the shard by his heard, but he does it before the events start unraveling.
4. I thought that the Mandarin looked like Warren Ellis (sorta).
For others, see below an image of what happens few days after being exposed to Extremis before the subject's body "reconfigures" itself. They didn't want Pepper Potts looking like this. Heh.
Re: Ellis
Haven't read Planetary, but both
Global Frequency and
Orbiter were really good. The first one even got a TV pilot, though the show never aired.
Lazarus Churchyard is pretty badass as well.