1. I told they are hybrids.
They aren't.
2. You are right with them being constructs.
3. I choose red/black because red is the standard color used for fleshies, but actually I am happy with any different color.
Text citation from
http://compendium.ddo.com/wiki/Race:Warforged official homepage
"Originally intended as nothing more than mindless war machines, the warforged acquired sentience due to the arcane experiments intended to improve these weapons of destruction. Through these experiments, the warforged moved away from being true constructs and became alive. The basic and most plentiful warforged are just slightly larger than humans. Larger varieties of warforged-like constructs can also be encountered, as these remnants of the Last War still exist."
How you interpret the sentence: "Through these experiments, the warforged moved away from being true constructs and became alive. " ? And what is the explanation they can be healed from healing spells.
Regards