1. What items, mobs, animals, biomes, blocks, and other stuff form Minecraft can I add into my game?
Pigs
cows
chickens
squids
dragons
ghasts
zombies
(creepers)
any of your own designs
advanced NPC's
2. Could I use a texture pack made for Minecraft for my game? With the designers permission. Use Sphax BDcraft. It is amazing
3.If I have the random "World" generator in my game will that be OK? Sure. Make citys naturally spawn
4.If I use OpenGL and Smooth Lightning will that be OK use stuff like on optifine and GLSL