If you're confused about what they need and why you should call them and ask them what copies of documents they need. The contact information should be on the notice.
Here's what I can tell you:
The Schedule 2 is for (electric vehicle) Credit Usage and Carryover which should have transmitted with your return. What wouldn't have transmitted with your return is the required certification letter. Certification approved by the Environmental Protection Division of the Department of Natural Resources must be included with the return when claiming the credit. The credit did expire on July 1, 2015, so only purchases in the first half of the year qualify.
The other state tax return(s) are usually requested if you took a credit for taxes paid to a different state so that you weren't double taxed on the same income (in GA and the other state). If you didn't claim this on return (verify this by looking at it) then you should ask them why they are requesting them.
You don't mention them asking about your High Deductible Health Plan but the deduction is for the premiums you paid out of pocket and was not the amount of your deductible; the deductible amount is what qualifies the plan as a high deductible health plan which yours did.
When you mail the state the information they requested, make sure that you send them a copy and retain your original with your tax records.
