Financial Queries I have

I used to work for a US MNC. I sold shares at a loss in US market. Can I balance that loss against the gain I have in the Indian Stock Market?

Lets say my income is Rs. 9,00,000 from salary and I earn 2,00,000 from stock market (Short-Term Capital Gain) in the financial year. Now will I need to pay the surcharge on income when it crosses Rs. 10,00,000 or is income from salary only factor while calculating surcharge above Rs. 10,00,000?

If I am calculating the tax on the Short Term Capital Gains I have from the stock market, then can I reduce the gains by showing the expenditure such as Internet expenses from the gain before calculating the tax?

Lets say I bought 1000 shares of company X at Rs 10 per share. My total Cost Price comes out to be Rs. 10000. Now the share price is at Rs 20. If I sell 500 shares at Rs. 20 within an year of purchasing the stocks, then I earn Rs. 10000. Now is my profit NILL for the purpose of calculating taxes or is it Rs. (500 * 20 - 500 *10) == Rs. 5000?