hello guys.. i have a couple question on swimming...

1) can we gain "six pack" from just swimming 5 times a week for an hour each session?

2) which swimming style is the best (i can swim non-stop breaststroke for one hour but it's boring, currently learning free style, but it's very tiring lol, and butterfly, it's very hard when u are trying to fly up and down the water.. guess i should practice it everyday to cope with the stamina i needed to swim those style right ?

3) i dont have trouble breathing using breaststroke, but i always exhausted when swimming free style, but not butterfly.. butterfly the problem i have is after a 5-6 fly, my shoulder getting tired and cant held my hand as good as b4 the 1-6th fly..