Makehuman model with rig in blender for animating

Hello everyone!,
I have created a makehuman model and as Skeleton selected the Unity3d.rig which i got from one of the forums in which it said it is compatible with the mecanin in Unity. I exported as fbx and used in Unity successfully. It animates same as the Unity default model(the animation is extracted from bvh to fbx using blender but was not good as the model was rotated 90 degrees Y-Axis and also hands where moving in wrong direction). Anyway my model worked same as the default model. I did not find any animation that worked perfectly with my model and also unity. Hence i decide to create my own animation in blender.

I am following this tutorial. As i am using the rig which i mentioned, the rig file is in my model. I can see it by clicking the + sign beside the model name. In that tutorial upto step 9 the creation of rig is explained.

Is the rig created along with my model from makehuman is enough for completing the remaining tutorial? Will my rig will be fully compatible when i export to Unity after animation?

Some basic question.
Which is the Controllers mentioned in step 10 second image?What is Vertex group? What is a weight painting and why is it necessary?

I am a beginner and hence these basic questions. Thank you