Intra Day Trading

Software or ITR utility itself adjusts the amount when previous year/s losses are entered in relevant schedule.

Check 'Schedule CLF' of ITR 3. 

As a rule it must be allowed. Its software glitch. Report the same to help-desk.

Yes, you are correct.

From this year CPC has removed speculative business from presumptive income declaration. 

You need to file it under normal assessment.