Yes.
25G is the gamer score (known as achievements). All games have this gamer score.
Pretty sure you can't. You can get 200 from arcade games though.
As of now there are no achievements in Indie games. Currently only Xbox Live Arcade Games and retail games have achievements. There is always the possibility of Microsoft adding support for Indie game achievements in the future. As of now, no achievements there.
By earning achievements in games, either retail games or Live Arcade games.
The redeem code is used to redeem Microsoft points. it costs Microsoft points to change your name on the xbox which you can buy from stores like game and other gaming stores and you can redeem them on the xbox to buy games and in this case, Change your name.
Yes, but they are not called achievements. They are equal to achievements an are called trophies. Only certain games on the ps3 have achivements, most of the new ones. Not all games have trophies, but the games that do, share the same trophies as xbox 360 achievements. There are bronze for easy achievements, silver for medium, gold for hard achievements, and platnium if you get all the achievements for 1 game, which is hard to do. Godfather 2 is very easy to do it, however.
Yes there are, for example Armor Games, or Canoop Arcade
The gamer score does not tell someone how good a player is. The gamer score only shows people how many games they have played and what achievements they have gained when playing the game.
yes but u need an internet connection. xbox live subscription and gamer points to pay for the actual games
No. A gamer is someone who plays games, that does not mean he is a gamer.
Xbox arcade games have a free trial but do not provide achievements. I have not come across a free arcade game with achievements. However, you can download the game arcade room which is free and have achievements.
The G represents your gamerscore which is the xbox way of rewarding you for completing achievements. In most games there is a 1000 Gamer points to be won.