batching draw calls for performance optimization

See more:

DirectX

i am using directx9 & i have created tree.x (3D model of Tree) having 5 material..
and a orientation list which contains orientation data such as 3dvector for position.

now suppose my orientation list contain 1000 of orientation so i am able to draw 1000 of trees.

i had already implemented frustum culling for performance optimization.

i read about batching draw calls. but not able to understand its implementation

now i had two question.
1) I am creating leaf of tree in 3 material for LOD (only one out of three is going to render at spacific distance)so increasing materials in .x file will decrease perfomance??

2)is there any way so that i can increase my performance??