Zero to three. This is an important area for parents to learn about. One great resource is www.Zerotothree.Org. Their website will answer the overview questions plus much more. Enjoy!
Touchpoints. Babies develop in many different ways. The most important thing is progression - some go faster than others in certain areas (fine motor, gross motor, verbal/language and social). There are too many stages to list here specifically. I like t. Berry brazelton's touchpoints model which allows for individual variation.
Far to many to say. There are far too many developmental stages to mention in a 400 word blurb. In general they are in 4 main catagories - language, gross motor, fine motor and social development.
Too Broad a Question. Unfortunately, we only get 400 characters to answer each question. I recommend going to the american academy of pediatrics website at aap.Org. The have a very good research section for parents on any topic. If you have a more specific question, please repost.