Placement of legend is the correct answer.
It totally depends upon whether modification is being done in somatic cells or germ cells. Somatic cells modification is ethically accepted because it doesn't pass from one generation to another generation but germline modification is considered as unethical because the modification will pass on to the next generation leading to the persistence of modification in future generations. The problem with genetic modifications is that the impacts of modifications are unpredictable, rather than being fruitful they may lead to lethal mutations so if it occurs in just somatic cells, then even if it is lethal/harmful, it will be confined to only that individual but if a lethal mutation occurs in germ cells then it will pass on to the subsequent generations and it will persist in all future generations.
4. Gene Pool is not a mechanism, thus your answer!
You should use a Punnett Square for this question
The Punnett square predicts the offspring of two parents (two alleles). In this case you have brown eyes (Bb) and blue eyes (bb)
In the four boxes you should have Bb, Bb, bb and bb (50% chance of offspring with blue eyes and 50% chance of offspring with brown eyes).
The genotypes ratio will be 2Bb:2bb
And the phenotypic ratio will be 2 Brown : 2 Blue