School Property taxes - We settled on a new home on 9/30/2016 and had to pay school taxes for 9/30/16 thru 6/30/17 at closing, Is this whole amt. tax deductible in 2016?

If you paid the whole amount in 2016 and the school taxes were accessed on the value of your home, then they are deductible in 2016, regardless of the period they cover.

Do I have the option to prorate and defer the 2017 portion in 2017 taxes if deductions for this year are max'd out?

No. The deduction is taken in the year it is paid.