If it is a partial Credit Memo, are shipping and handling cost per lines re-calculated?
Yes, changes in the line item (e.g. quantity, amount) will trigger the system to set the Shipping Cost to recalculate wherein the user has to click on the Calculate link. Alternatively, users can go to the Shipping > Shipment subtab > then click on the Calculate Shipping button.
Will there be any changes in the shipping cost when a Credit Memo is created from Invoice?
None. The information will be carried over from the Invoice to the Credit Memo.
Can you manually change the values of the shipping cost when a Credit Memo is created from an Invoice?
Yes.
Is MSR available in the web store?
No. It is not yet available per Enhancement Number 186023 (Webstore Shipping: Customer would like to have the ability to select multiple Shipping Costs per line item on Sales Orders. This will allow them to add extra shipping charge on some bulky items)
Is MSR available in Return Authorizations?
No. It is not currently supported.