Pardon me for invading your thread without critique, but I'd like to offer my 2 cents in the whole character design <-> world relationship. You said in an earlier post that your character's design influence the world. I beg to differ; I think the world is what determines the design of your character.
There are physical aspects that you briefly touched like the vastness of the world. OK. That's one. Now, think about what are the consequences of such a world? Is transportation going to be super-duper advanced? Is telecommunications possible? What is the technology like?
Countries/territorial boundaries, do they exist? Are there governments or any figures of authority? Social classes?
Do water even exist here? Will humans need to adapt their needs, grow wings, fins, massive noses?
NOW. Temperature. Holy hell your world will have a huge effect on your characters. Will there be a concept of DAY and NIGHT? In that case, will there be Day creatures or Night creatures?
... you see where I'm heading with this?