In my cart I have customers choose the weight of their product (dog treat, different sized bags)
Do I need to make each weight bag a separate Item in the shopping cart in order for the weight based shipping to work correctly?

Or can I allow the customer to choose separately which sized bag they want and charge them that way?

Other question,
Is it easier to do weight based this way or just do manual shipping? What if they get over charged by accident?
Which have ya'll found as the easier shipping option and who do you use?

Thanks,
-Laurence