How to prolong battery life
Here is a place you can learn all about Batteries.

Battery University.

and from Apple here

To you question on 8+ hour, the new MacBook Air (2104 model) has that.


  The 11-inch MacBook Air lasts up to 9 hours between charges and the
  13-inch model lasts up to an incredible 12 hours.


The cycle count is only one of the indicator and can not be used as absolute measure of Battery status. You need to look at the Full Charged Capacity (in About This Mac- Power)to get total understanding of the battery status. That one indicates the capability of the battery to hold the charge indicating how many cells are not doing so well and not holding the charge.

With all that said, if you use the battery in the Apple prescribed manner, you can not prolog its life beyond the original design, or beyond the physics and chemistry involved. For example a battery will develop short circuits due to build up of Whiskers (growth of Li metal deposits) that short out portions of the cells during its life and there is not much you can do about that.