Parody can be fair use (http://www.law.cornell.edu/uscode/17/107.html; caution annoying interstitial) and protected internationally I gather but is not always. The original costume probably could pass as a parody (or be deemed personal use) and so be fair use whilst this comic-book image doesn't look parodical it's just a commercially used derivative in a different media.
Adaptations of other's work (that use a "substantial part") are not allowed without permission of the original creator.
Tracings? You think it's OK to duplicate someone else's copyright work as long as you trace it? That's almost the definition of a slavish copy - like considering copy-pasting the binary presentation of an MP3 to circumvent the creators rights.
Marvel are presumably distributing this internationally? Remember that fair use is a lot narrower in some non-USA jurisdictions.
Lastly, is the owner of the convention photo copyright sure that this is a copy of his image. Presumably others could have taken pictures of this guy at the same time?