Some tomato varieties just crack and there is nothing you can do to stop it. Next year buy a different variety.
Depending on the size of the seeds you want and what you want to do with them, you can pick lmost any size. Commercial sweet pickles are picked almost as soon as they were set. Larger cucs are harvested after they swell and become fairly smooth. Seeds are also swollen and large. Ripe cucs are actually yellowish orange, are edible and do NOT store. Hence cucs are picked green (unripe) for sale or storage. Ripe cucs are picked if the seeds are to be harvested. Really long cucs are called yard longs because they often get 18 or more inches long. You may have this variety - hence the long skiny cucs. I like to pick my cucks when they are still "wrinkly" because the seeds are smaller/not filled out and thus more digestable.
