Hedonism is a philosophy which picks up where the investigative philosophies leave off. It doesn't tell you what to do, only "just do it." :)
>>> What are we?
Carbon based lifeforms.
>>> Where did we come from?
That's rather moot at this point. (see investigative philosophies)
>>> Why are we here, what is our purpose?
There is no explanation to why we are here but we are relatively free to dictate our own purpose. Therefore we should do what best approximates what we actually want. With advanced technologies, we can go much further than we could before.
>>> Where are we going or what happens when we die?
Reach behind your computer and pull the plug. -- Exactly that; party's over. =(