R.R.
18 months is worse than 2, in my opinion! My son was a terrible 18 month old and a not so bad 2 year old.
Very normal for them to be picky and have a real limited repertoire of foods at this point. Even if he just eats some fruits, yogurt, cheese, eggs, and whole grain bread with peanut butter and honey or sugar free jelly, and soups (with veggies pureed in) you should be ok. I have found the best way to get them to eat well is to always eat together as a family. Saying a prayer or lighting a candle can be a nice way to signal a special time- a family meal- is beginning. Stick with it, and I bet you if you all sit together and YOU set the example, not getting up or starting dishes- his ability to eat will improve. Also, cut down on fruit juice if he is having that- it seems to be a meal spoiler for my kids.
Is he watching tv? TV is a huge cause of frantic and hyper behaviour. Tantrums seem to be a kids way of telling you some part of his day is frustrating to him. Slowing down the pace and having regular special rituals for how you do things can really make a huge difference. Tv watching also slows down speech- because speech, developmentally, is very tied to movement (speech therapists will even employ crawling exercises to help young children with speech- something about moving you opposite arms and legs helps coordinate interaction and neural pathways between right and left sides of the brain, which also helps with communication). TV time means less movement- more sitting still. Less opportunity for body movement and the heatlhy brain stimulation movement and interaction with his environment will spark.
Try reading "Heaven on Earth: A Handbook for Parents with Young Children"- it has been a godsend for me. It's not so much about discipline, more about how to create an environment that will be very joyous for you and your kids.