I can’t help you with the first two questions, as I do not have a reference, but I can help you with the last two. Cystic fibrosis is a recessive trait. It is caused when specific sections of both copies of chromosome 8 are deleted, which in other words mean that it is not a sex-linked disorder because it isn’t inherited from the mother and father of the offspring.
No, all mutations are not bad. Only a small amount of mutations cause genetic disorder. Some in fact are good mutations. There is actually one mutation that is found roughly in 10% of Europeans which affects the CCR5 protein and it prevents HIV from entering the cell!
