Are identical twins more common than fraternal twins?
No, about 1 in every 3 twins is an identical twin.Source: http://twins.usc.edu/about.htm
Which is more common fraternal twins or identical twins?
Fraternal twins are more popular.
If identical twins had babies with identical twins, would the children be biologically siblings?
Biologically they'd be full siblings, if their twin parents married singlets their cousins would be biologically half siblings.
If a girl slept with two identical twins and got pregnant, would both twins...?
I Think the Careful Analysis of the DNA (Germline), Would Reveal Some Difference. E. g., the Incorporation, of Viral DNA.
How can you become better and cooler than your identical twin if both twins are both good?
depends on what you mean by better, one twin is evil and the others good