You can use ITR 4 and just show minimum 50% amount as income.
No one needs to file one ITR for all income. You can read more here: https://www.taxontips.com/top-myths-relating-to-income-tax-return-busted/
You can avail depending on how the company has shown your services other than 194J section. Have you issued any bills?
You can mention them as zero if you don't have any.
No.
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