• Capital gains tax

As per CBDT circulars Assessee has option to show Profits from shares as business income or Capital Gain. However, for frequent trading it has to be shown as business income. However, for Long term capital gains, he can choose the option of LTG and Assessing Officer cannot dispute it (my understanding). 
Question is can a person who buys and sells shares frequently show his income under Business and Profession and for long term gains under capital gains? Or is it that once you chose to show under Business Income you also have to show long term capital gains also under business income. The 3 CBDT circulars on this issue are not clear. 

2nd question is shares bought and sold the same day without taking delivery as speculative gains or losses under head business income. What is the treatment for shares bought today but sold the next day BTST? Delivery of shares is taken by broker but since they are sold off the next day they don’t enter clients demat account.

3rd question in about FnO profits. All expenses like brokerage, STT, exchange fees, sebi fees, gst, stamp duty are allowable. Besides these expenses I have incurred nothing as such other than nominal broad band and electric charges. How can I reduce my tax liability legally.

4th and last question: FnO turnover is computed as per guidance given by ICAI. Absolute of positive and negative differences and premium received on sale of options etc. Can I use this figure of turnover and pay tax at 6% under presumptive scheme? 
My turnover as per ICAi method is Rs. 2 cr but otherwise 196 cr. Profits about 90 lacs.