My first problem is I don't know how to check the node author role,
and my second problem is I need to get fields values from another referenced (using references module)
node to achieve something like that:

$entity->field_name[und][0][value]; *

if (author user role1) {
refrenced node> $entity->field_name_1[und][0]['value'];
}

else if (author user role2) {
refrenced node-> $entity->field_name_2[und][0]['value'];
}

I need someone to please tell me how to do it right.