How many 本 are in the series and in what order do they go?

The エンジェル Experiment
Schools Out- Forever
Saving the World and Other Extreme Sports
The Final Warning
Max
Fang
エンジェル
And the last one coming out on August 6, 2012 is Nevermore.

The first book is The エンジェル experiment the 秒 is Schools out forever the third book is Saving the world and other extereme sports the fourth book is The final warning the fifth book is Max the sixth book is Fang the seventh book is Angel
And coming soon is the eighth and final book of maximum ride is Nevermore

The order is:

Maximum Ride: The エンジェル Experiment
Maximum Ride: School's out forever
Maximum Ride: Saving the world and other extreme sports
Maximum Ride: The Final Warning
Maximum Ride: Max
Maximum Ride: Fang
Maximum Ride: Angel
Maximum Ride: Nevermore
Maximum Ride: For