Not unless you create a new Apple ID. Your apps and media are tied to your Apple ID. So, as long as you continue to use the same Apple ID that was used during previous purchases, your content should always be available to you without the need to purchase it again.
Creating a new Apple ID would create a situation in which you are starting with a clean slate, as if you never had an Apple ID in the past.
Don't worry about the sizing aspect if the app was made for the iphone there is a 1x/2x setting that will enlarge the app on your screen without the loss of clarity