I completed the full KYC on my NSDL account 4 months ago when I read that some accounts were starting to get blocked. So, in my case it won't get automatically closed.
Correct, charges are for account maintenance. Ab RBI toh yehi kehta hai ki negative balance nhi kar sakti banks, but banks kar deti hai and phir closing time par shayad bank wale bole ki clear karo dues.
Still before 18 months toh point hi nhi close karna ka, 590 le lenge woh. Clearly mentioned hai website par so RBIO won't help us in this.