So first steps should be email client and free email service like Gmail, and maybe social network
Well, as for email, I would never entrust my mail to a FOSS mail provider, as security is complex and hard to do right and uptime can be quite critical. FOSS developers usually do neither have time, nor money, to spend on those. I would welcome a company going opensource, however! At the moment, I go with a FOSS client plus a commercial mail provider (I pay money directly). As for the social network, have you ever heard of Diaspora? It is a distributed social network.
What do you think?
I think, your ambitions are admirable, however there already are projects like that and you just have to google a bit to find them. Take a look at them, first, because it makes a lot more sense to contribute to existing projects, if they suite your needs.