Slugs live just under the soil during the day, staying cool and moist and feed at night. You can trap then easily enough using a wide board or roof shingle where they will go after feeding. Lay this between the rows. Sometime during the day, pick up the trap material and dispose of the slugs as you see fit. There are baits available as well from Garden Centers that are applied to the soil.
Your eggplant is being eaten by a small black beetle called Flea Beetle. It only eats the foliage. A foliar spray for chewing insects could be applied if needed. Follow the directions carefully and note the days till harvest.
