Custom Shipping rates and Weight calculation

[whiplash]

Hi 

i have question about Shipping and fulfillment

1, calculate the weight of the products and parts in the cart (there is a file for each part and weight) 

2. Fedex price lists are available, so customers can specify the weight and area to be transported.

in this case do i have to setup shipping rates and add the kg of the products ? or do i have to use the shopify app ?