Well, if you're going to try and modify the objects and textures in the game, then good luck. It's next to impossible to add new items to the game, let alone modify the existing ones. If it was even moderately easy, thee would be a TON of new texture/object packs out there, dontcha think?
If you just want to make a safari, you could create savannahs and jungles with existing textures and objects, and add the cheesy animal statues as animals.