With respect to 179 deductions, can I apply half the expense in 2015 and the other half in 2016? Or can I only do half now and the rest over several years?

No, you must claim Section 179 deductions for equipment and/or vehicles in the tax year that the item was "placed in service" - meaning when the item is ready and available. 

Please be advised: If you chose not to take the full Section 179 deduction, you may be able to take a one-time special allowance depreciation. After entering the percentage of the 179 deductions, the system will move you to the special allowance depreciation option. Please note that not every state follows the federal rules for depreciation.

Please visit 179 Vehicle Deductions for more information.