Newbie questions about Tor, I2P...

Hello guys!

First, i must tell You that site is excellent especially for the beginner like me! So now i have beginners question for You :)

I read it what You wrote about Tor, I2P etc...When i buy new lap top i planning to beginn from a start, installing Tor, I2P...

Btw i use Ubuntu. Please tell me, how in that case i can use my public e-mail, profiles like Facebook and others, in the same time with new non public e-mail and anonymous profiles...?! Do i need different browsers, for ex. Arora for public "relations" and Firefox with Tor button for anonymity...?! Is that even possible and good for being anonymous...?! Or i need to have multi boot like i have now and use just one OS particular..?! Or...

Guys, im be glad that You help me solving my confusion, i definitely want to be "anonymous" in the near future, but i want to know how, when to use public profiles but to not disrupt anonymity...Sorry if my english is not enough good and hope You will understand me :)

Thanks!