1.say - Is it any determinating right or something?
2.given those - I'd like to know its contextual meaning, I think it is "Though it was given those..." not "If it was given those.." the latter sounds awkward. Which do you think is proper? My book's translation goes for the latter.
ex)If you compare a walnut with some of the beautiful and exciting things that grow on our planet, it does not seem to be a marvelous creation.....Its growth is limited by the hard shell that surrounds it - the shell from which it never escapes during its lifetime. Of course, that is the wrong way to judge a walnut....It had no say in the size or shape of that shell. However, given those limitations, it achieved its full growth. How lucky we will be if, like the walnut, we blossom and bloom in every aspect of the life that is given us.
#2. Doesn't make sense to me.
Given something = because of somethingHowever, given those limitations, it achieved its full growth.
ex. Given your weight, it's no wonder that the chair broke when you sat on it.
The sentence you quote would make more sense if it said "despite those limitations...".
Perhaps someone else can give a differing opinion.