Hello Avenged Sevenfold,
Cain was able to marry a close relative.
The objections we have to this did not stand at the beginning:
The genetic pool was much purer, so the danger of inherited disease was not yet a problem.
God didn't forbid these marriages until later, at the time of the Exodus, when this deterioration may have become sufficient to require the new law.
The race issue is addressed well here:
http://www.answersingenesis.org/Home/Area/AnswersBook/races18.asp
In a nutshell -
We are all one race - the human race, descended form one couple who had all the genetic information in them, and passed differing bits of that on to their many children.
People moved apart, and each group took only certain genetic information, leading to the loss of many genetic characteristics.
Regarding an avatar, you need 200 blessings first.
Scroll down the forums and you'll find the relevant place for instructions.
Blessings, Susana