Tax exeption

My friend  works as a service technician or consultant as a profession. He does not maintain books of account for the receipts as well as  expenditure incurred for his travelling and other daily expenses.

Is there any statutory exemption to deduct a fix amount for these expenditures. If it is, then what is the percentage?

Can he claim expenditure on medical bills, travel, lic and accomadation without attaching documents to the ITR 4 form while filing tax return?

Please guide us.

Thanks.