where to start from. and what all i should consider in building a hybrid go kart
Not an easy question ,but there are special schools for automotive engineers.
You have to study 3 or 4 years to become a car designer/engineer.
So perhaps this is a start...
Than learn to master a 3D modeling program/software.
Combine the two and there you are...able to design a hybrid go cart.
I hope this is helpfull.