2. Interest should be shown under ‘Income from Other Sources’ because it is a taxable income eligible for deduction u/s 80TTA.
Under deduction concept, the amount is first included in the gross income and then deduction is claimed, to the permissible limit, to arrive at the total income.
As per your understanding, its exempt income concept, where the income is not considered as a part of total income and the whole amount is exempt for the taxpayer. However, we need to report it in the ITR under exempt income for reporting purpose only.
So, first include 4K interest income under IOS and then claim deduction for the same. If interest is > Rs. 10,000 in a F.Y., the difference will attract tax. Since, your interest income from the savings accounts is < Rs. 10,000, you don’t have to pay any tax on it.
3. Where to report in the ITR?
ITR1: B3 - Income from Other Sources (net amount of OS)
ITR2: Schedule OS – 1b (Interest, Gross)
4. Wait for someone else to answer this query.