The possibilities for salads are pretty much limitless. There's fruit salads, chopped salads, fresh greenery salads, herb salads, dessert salads. And each recipe can modified to make a different salad.
It really depends on the rest of the ingredients in the salad as well as the type and amount of dressing used. You can expect that there will be at least 130 calories per serving. You can calorie check at peertrainer.com.
The healthiest salad dressing is one that is fat free. Generally Balsamic Vinaigrette has the lowest calories and zero fat. Look for light versions and anything that is not creamy.
A large kitchen knife has always worked for me to cut up the lettuce as soon as I get it home from the store. Then with a seal tight salad bowl, I put the leaves in the refrigerator. It stays fresh for days!
Wow to give you one simply answer is impossible. As there are many great books out there on the art of salad making. Some of my top choices are: The Art Of Salad Making by Carol Truax and Simply Salads by Jennifer Chandler. Both offer great and easy recipes for the salad lover.