1. Atheism is not a philosophy, per se. It is a component of philosophy. It can be a derivative of a philosophy or it can be a (partial) basis for a philosophy. It can be an ancillary or ad hoc portion of a philosophy, but it isn't a philosophy unto itself.

2. Atheists may or may not mean the same thing by the term 'atheism' that you do when you use the term.

3. I have always acknowledged that there are multiple definitions of 'god'; however, those definitions are can be categorized or grouped. I have expressed my opinion on a number of different views here: http://www.youtube.com/watch?v=OgtoaVACidw

Of course, most people who have religious beliefs resist having their beliefs categorized, because their views are obviously correct and more sophisticated than the others in the category.

"See, those OTHER guys, they argue over whether god wears a BLUE shirt or a RED shirt, but we sophisticates realize that god doesn't even WEAR a shirt!"