You can handle removing shipping cost based on the price of the order by using an "if" statement in your shipping formula. So say you want to charge $20 for shipping but if the order price is over $500, then shipping is free, then you'd write a formula like this: price > 500 ? 0 : 20(this reads as "if price is great than 500 then shipping cost is $0, otherwise it's $20")
