As I'm posting my take on various aliens and such from comics, TV, movies, and other games, I thought it might be somewhat helpful to understand my thoughts behind the conversions.
First off, I don't really care about staying overly true to the original representations. This has been pretty evident with my write-ups recently. The Kree, Shi'ar, and Autocrons all can lift over a ton in the Marvel Universe (5 tons for Autocrons). I don't want Mythic Space to turn into a Rifts-like arms race to see who can build the most unkillable PC, so I'm dialing that kind of thing way back. The Skrulls also got dialed back. There are no Super-Skrulls walking around mimicking mutant powers. They can't even shapeshift into specific people! However, their ability is still pretty damn useful, especially in a campaign that's high on spying or subterfuge in general. You'll see this the more I post other species. Vulcans are more human and less "Logical Mary-Sue" like they sometimes are portrayed to be in the various Star Trek series/movies/books, for instance.
This goes for background information as well. Take the Autocrons I just posted. In the Marvel Universe, they hail from the sixth planet in the Betelgeuse system. Since Betelgeusians are a member of the Concord and that system is deep within Concord-controlled space, I didn't want an Autocron empire in the middle of it, so I sent them off to the Fringe of the Orion Arm; still close enough to be a problem, but not right in the mix. Plus, I tied them more into my setting by giving them a deep hatred of two Star Trek species. They are still Autocrons, but now they are Mythic Space Autocrons rather than being solely Autocrons from the Marvel Universe.
My bottom-line philosophy in adapting material is "spirit, not the word." When someone in my campaign decides to play an Eldar, Luxan, Shi'ar, Wookiee or whatever I want them to be relatively on par with they other characters in the group mechanically, and I want that character to have enough cultural background info (and stats) to make the player feel like they really are playing a member well-known species...even if they can't throw a 2 ton crate across the cargo bay!
So there you go, a little look into the cluttered mess that is my mind!