How much rupees stamp should i paste?

I want to send a greeting card to my friend from kumbakonam to chennai through much rupees stamp should i paste on it..i dont have time to ask in the post office.i plan to post it in the postbox near my house..the greeting card is quite big. 30cm *15cm in size..Can i post it in a post box?

Can a bank fine a customer for paying in cash?

I have paid the dues to my credit card in cash. The bank is levying a penalty of 100 rupees for cash payment. Are they entitled to penalise me to use the legal tender in settlement of my debt. Under which law I can get relief.