Income tax for mobile developer earning only from app store

I have mobile app earning revenue from download of paid version and advertisement revenue in free version. The total receipt is bit over INR 10,00,000. There was no books of accounts maintained as there is no daily exchange of cash/money, only monthly payment from the App store are credited to a savings account. As the sales are indirect (Store deals with the customers), and considering the service is exported, no service tax registration was made from my side, nor any service tax paid. There is no registered company by my name and the App store account plus income is individual and paid on a savings account. 1. Presume the applicable file is ITR3 for FY 15-17. Is there a chance of such income quality for presumptive taxation and fill ITR4? 2. Considering ITR 3, "Balance Sheet" section, can I just fill in the "NO ACCOUNT CASE" section 6 (d) and put the net income there? 3. Considering ITR 3, P&L Account section, can I just fill in the "NO ACCOUNT CASE" section 53 (I) 4. My last year gross receipt was also above 10 lacs but not significant the year before. So, what kind of problems the non maintenance of books can pose later? 5. Is there a quick way to build a book of account now (as for the income it does not qualify for audit), I could say it was maintained throughout the year? Or is it better to use "NO ACCOUNT CASE" I know the questions are direct and responses might be sensitive, can someone please point me to the right direction?