My IP and copyright

Hello,
first, I am sorry, but my English skills arent so high to find anything on this forum, and sorry for my English.
So, I am making a game.
1.Can I name it as I want? (I wont use any licenced word) For exapmle: I want it call Age of Ants, but there does exist game called Age of Ants: http://games.t45ol.com/play/1930/age-of-ants.html , so do they have licenced this name?
2.When I create game with non-yet-used name. Will be this name my? Or someone other can use this name too? (my game will be free, but official)
3. If someone can use that name too, how can I register my game's name, so he couldnt use it anymore? How would it cost(approx)?
4.Will be that game my IP after creating it?

Thanks for respond