Sounds like flea beatle damage. They love young tomato plants, and can be a real problem. When they start I immediately (that day or the next) spray the plants with insecticidal soap, or worse. After the plants grow for a couple of weeks they don't seem to be bothered bothered any more.
If you know that you are going to have a problem you can plant radishes nearby as a trap crop. The flea beatles will prefer the radishes to other vegetables.
The wilting is probably caused by high water loss. Greenhouse grown seedlings are not adapted to life outdoors, and their roots can't keep up with the higher water loss. Little pots also can dry out very quickly so make certain that the pots are wet when you put them out in the morning.