Answers

Get with a local solar company and have them look at your plans.  You may be building a home that cannot work with solar due to your roof pitch, orientation or shade.  Let them give you a site assessment and run the financials based on your available incentives.  You can look them up here:  http://dsireusa.org/

Your federal tax credit is 30% through 2016.  For your state tax credit see http://dsireusa.org/

In Louisiana you can get 30% plus 50% on a system that costs $25,000, so you would get $20,000 here!