Build a postcode shipping calculator for shopify

We are an Australia store and need help to setup a suitable shipping method for Shopify. We both deliver and have “in store” pickup for customers. “In store” pickup is currently configured with the app “Delivery and pickup” by zapiet. 1 ) We deliver to a limited range of postcodes. Ie, if the postcode is not listed in any of our delivery zones (postcode range eg. 6001,6002,6003). Then the customer will be advised we cannot deliver to their area and they will be unable to complete their order. 2) Some postcode ranges will have a flat shipping cost whatever the weight of the good they order. 3 a) Some postcode ranges will be charged based on a per KG rate. Eg if the rate per kg is $40 and their order contains items of a total weight of 2.5kg they will be charged $40 x 2.5kg = $100 for shipping. 3 b) The postcode ranges will need to have a minimum order weight set for each. For example 1kg, so if the total goods weight less than1 kg they will be charged for a minimum of 1kg for shipping. 4 ) We would like to have delivery messages attached to each of the defined postcode ranges. For example “Estimated Delivery time 4 weeks”. Please advise if this is possible. We have a short time frame to complete this project.