Answers

I can't connect to my home wireless connection via networkmanager

Yeah, i can't.

Even if i could, when i was using archlinux on this laptop before installing development elementary 0.2 Luna.

The strange thing is that i can connect to a wireless free connection near my home...but it is useless because it's really slow.

Any idea? Must i install any packages? (sorry but i do not use .deb since 2-3 years)