Read dead redemption *SPOILER*

GAME: ReadDead Redemption
ACHIEVEMENT: All of the secret ones
GAMERSCORE EARNT: unknown
ACHIEVEMENT INFO: Unknown

Hey I was wondering what all the secret achievements are in red dead and how to obtain them, aswel as the avatar unlocks.
any help would be really appriciated!

Heading south on a white bronco-Evade the US marshals while riding the hungarian half-bred horse in Single Player 5G

Manifest Destiny-Kill the last buffalo in the Great Plains in Single Player 5G

Spurred to Victory-Complete 20 story missions without switching to a new horse at a hitching post 10G

Dastardly-Place a hogtied woman on the train track and witness her death by train 5G

That Government Boy-Complete Exodus in America 10G

Land of Opportunity-Complete The assault on Fort Mercer 30G

Sons of Mexico-Complete The Gates of El Presidio 40G

No More Fancy Words-Complete An Appointed Time 20G

A Savage Soul-Complete At Home with Dutch 10G

The Benefits of Civilization-Complete And the Truth Will Set You Free 90G

Into the Sunset-Complete The Last Enemy That Shall Be Destroyed 100G

Nurture or Nature?-Complete Remember My Family 50G

Hope this helps you out

Thanks for that 'G' thats really helped!