Use correlation matrix scores as starting weights and bias inputs for neural network?
The way I see it is that NN can learn nonlinear features, so I wonder: does your correlation matrix on the raw data take into account nonlinear connections between features to see the full picture? Probably, it doesn't. As the topic is not about the single-layer nn (which would be an example of linear regression), the final connections (values of each weight) will be created by the contribution of many layers. Therefor it seems to me, that setting start weights on the proposed way wouldn't be high relevant.  

Speaking about imbalancing, I'd recommend to experiment with loss functions. You can set higher penalty for mistakes on a certain class.