TAXABILITY ON FREELANCE INCOME

My son, who is ordinarily a resident Indian, works on FREELANCE to some foreign establishments and receives payments through PAYPAL to the credit of his ordinary SB account. No TDS is deducted.
 

Please guide regarding the

1. taxability of the income

2. if taxable, what are the taxes

3. what are the returns to be filled

4. is ONLINE FILING possible