Question on raw cocoa powder?

There's many articles saying that using raw cocoa power to make drink is better than eating chocolate(unless the chocolate is made of 75% cocoa or more).And now i'm using Van Houten cocoa power,please let me know about:
1.How much cocoa is need(or good) for health per day??how many gram/spoon should i used(i used raw cocoa powder with sweetened milk)
2.They said that using too much cocoa can't cause problems in calcium absorption,so how much is to much???
3.They say that cocoa contains very much of the anti-aging agent,so comparing between a cup of cocoa and a cup of green-tea( i've heard that green-tea contains the anti-aging guy as well),which contains more of the anti-aging agent???
4.On Van Houten cocoa,can anybody tell me if i'm using the right supplier coz in my place,Van Houten is the best i can got,the rest,in my opinion,are just trash and aren't even worth looking.
5.finally,please tell me what the 2% milk means??
thank you all my friend!