Edit Zen Cart Checkout System

I need to make changes to my Zen Cart website's checkout process. I'm not sure if my existing checkout system can be modified in order to do what I want below, or if I need an entirely different checkout system. Please advise. site: [login to view URL] 1. make the shipping step first, then billing and payment second. 2. remove mr. and mrs. field. 3. remove "country" option (default should be United States only). 4. make billing and payment on the same page (2nd page). 5. on shipping page... change the words "Special Instructions or Comments About Your Order" to "Gift Message Option" with a brief description on how to add a gift message below it. This field should be limited to 250 characters. 6. on shipping page... add a future delivery dates drop-down menu (so the customer can choose a future delivery date 3 or more days in advance). 7. allow customer the ability to move back and forth between checkout pages. 8. change the account creation page so that it is the same fields as the billing page with login details. 9. on the shipping page... change the words "per item" to "flat rate shipping" and the words "best way" to "USPS Priority Mail (2-5 business days)". 10. remove address auto-fill feature. Right now when the customer fills in the first address of the order, the second address is automatically filled in. Remove this feature so that both address forms are blank and the customer has the option to auto-fill if he so chooses. For example "check here if billing address is the same as shipping address". 11. create an option for the customer to log out. (There is currently no way for the customer to log out). Some of these steps are quick and easy, but some of them will take time. This is an important project to me and I will not consider freelancers who want to fly through this and only finish some of the points. Please look at my site before bidding and honestly tell me what you can offer. Price is very important to me.