Regarding A Quiz App That I Am Going To Develop

I am planning to develop an android quiz app. This works like this. Two people would invest some money and play the quiz. Whoever gets the highest points would win all the money minus some commission. I have two queries here. I believe as the game involves skill and talent, it should be legal. So, whose permissions should I seek before releasing the app as it has money related to it? Also, if possible can you please let me know how to pay the income tax once I release the app and generate some income.