consumption of firewood and HSN code

As a registered brick manufacturer, we have to consume a bulk quantity of firewood during firing of brick. Most of the seller are unregistered. Please let me know sir, ...
Q.1-what about gst if purchased from urd.
Q.2- can I treat the purchase as daily basis (5000/-per day)
Q.3- if yes, then do I need to raise self invoice for the above Said purchase
Q.4- what is hsn of firewood
Q.5- Do I need to raise self invoice for all purchases from urd (5000/-per day) separately if each of the transaction is more than ₹200/-
Please help. Looking forward to your valuable suggestions...