Exporting exisable goods with domestic sale

we are excisable manufacturing firm currenlty engaged in domestic sale, and some import also. We are planning to start export, so my questions are: 1. what are the excise fomalties for the same. 2. will the import of raw material duty free or eligible to duty drawback or else? 3. if duty concession or duty drawback is applicable then how the department will determine that which imported material we have used for domestic sale, and which for export. how these all accounting will be done. Sorry for my poor english.