I will usually design the breast pocket to be about 1 cm larger in diameter than the base diameter of the implant. This allows some room in the pocket to enhance implant mobility assisted by postop massaging to try to maintain a soft result. It is also important to consider the...
I think a natural look is always best.As a plastic surgeon I will make the pocket and once doen I will have available a variety of sizes and will put in a 200,then a 225 then a 250 until I get one that is full and natural.
Exercising prior to breast augmentation should not be a problem. Afterwards, you will need to hold off on upper body excercises for a few weeks or until you're comfortable.