I've heard that the character strengths are about the same, but in different ways. You have a different relationship with everyone, so you can choose to be friends, best friends, enemies, or just acquaintances. Although, people may die in the plot of you don't have their trust, so it's best to be friends with everyone.
I haven't played Mass Effect, but if those characters are even half as good as the ones in The Last of Us (my favourite game) then I can see where you're coming from.
Probably! I wanted to be a video game tester for a while until I realized that you would basically hate whatever game you were testing. That doesn't sound like fun.