Is it mandatory to replicate all sales order to ECC?

Greetings Friends,

We are using ECC as back end system. We have CRM sales in which we make oppr, qout and sales order. I have two questions:

1. Now, if any item in sales order required delivery what documents we need to create for logistic process in ECC?

2. If item does not need any logistic operations to be performed, do we still need to replicate this order in ECC? And if yes what configuration need to be performed?

I appreciate your valuable time and efforts.

Thanks,

Dhimant