You need to pay more attention because it's been said a million times.

The sand is Shukaku trying to protect its host, just like how Kyuubi regenerated Naruto. Because if Gaara dies, Shukaku dies.

The whole thing about the sand being Gaara's mother is just what Gaara thinks sometimes because Gaara is batshit insane.

And Gaara put that love symbol on his face himself. Seriously, you need to go back and watch Gaara's childhood flashbacks.