Bank details form 108

Yes.. it is the proof for payment of stipend by your principal..its just a formality to mention ...ICAI will not verify whether stipend is credited in your account or not.. .

I didnt provide anything in mine. And it went well. So i guess it is not required

no it is not compulsory....if your Principal is paying ur stipend by cheque no need to give bank account details but if ur stipend is directly deposited by ur Principal to your bank account then only bank account details are required.