Zen Cart shipping system

I need following kind of shipping system/item classification system for my Zen Cart site: 1. I need a system in which I can set up items to be BIG or SMALL (parcel or letter), depending on the size of the item. I need to be able to do this for each individual item in my store. It would be good if: - You could set up the system so that all the items that are in the store now would be SMALL. (- If I could update these with the Quick Update -tool.) 2. I need shipping prices for 6 different classes. A. Inland shipping B. International shipping 1 C. International shipping 2 D. International shipping 3 E. International shipping 4 F. International shipping 5 For A I would need: Shipping options SMALL: Letter, "payment on delivery" letter, pick up or special delivery. Shipping options BIG: Parcel, "payment on delivery" parcel, pick up or special delivery. For B-E: Shipping options SMALL: Letter Priority, Letter Economy, Special delivery Shipping options BIG: Parcel Priority, Parcel Priority, Special delivery For F: Shipping options SMALL: Letter Priority, Letter Economy, Special delivery, Cheap delivery (fixed price) Shipping options BIG: Parcel Priority, Parcel Priority, Special delivery, Cheap delivery (fixed price) It would be good, if I could add more International shipping groups later. System works like this: For orders with only letter-type (SMALL) items, items can weight up to 500 grams total and after that weight limit, the order would jump to parcel prices. System should add 5 grams of packaging for each item. I currently have all the item weights in the system for calculations. Orders with BIG items in them will be parcel even if they weight 2 grams. System should add 50 g for packaging for each item. I can send list of countries + prices when you need them. Note! The prices and weight limits have to be easily adjustable since my post office updates prices at least twice a year. 3. When choosing payment methods, if you choose "payment on delivery" only "pick up" or "payment on delivery" -options would be avaible (not normal letter/parcel or special delivery). At this moment you can choose "payment on delivery" and then choose any shipping method which is an issue. I would need system to work during November.