Also Is there any scripts where you can just paint grass(vegetation) onto another object (ground) like hair in blender render particle system. It’s just a pain having to manually shift + D a plane 1000 times
Its sound like you need to dubliverts or add particle emitter.
Probably the closest you can do is use arrays to duplicate the planes.
Duplicating planes is a terrible way to do it. Best way is to use a GLSL shader that does that for you. Check out benj’s method of doing it (http://www.blenderartists.org/forum/showthread.php?256768-Terrrain-LOD-UPDATE-physics-!!-huge-open-world-for-all-(glsl-custom-shader)/page6). You can paint your grass onto a stencil image and the shader will do all the hard work for you. You can achieve massive areas of grass without having to duplicated and position anything.
Benj’s method might be a bit ‘too much’ for your needs, but if you want something powerful and scaleable, then learn how he did it. The python code and GLSL code is fairly simple to follow, so have a look through the blend file he proved in the thread and figure it out.
Or the “old” Yo Frankie one: