Customizing of Magento checkout page

Customizing of Magento checkout page The text in the “2. Billing”page (checkout) „Adresse (Kein Versand an Packstation möglich)“ should be changed to „Straße und Hausnummer (Kein Versand an Packstation möglich)“ (see attachement 1) Add an additional tab calls “4. Groupon” to the checkout. (see attachement 2) In the “2. Billing” page, I have added two additional fields “Groupon Gutscheincode (Sonst "0" eingeben) *” and “Groupon Security Code (Sonst "0" eingeben) *” by installing the extension “order attributes” from Amasty. This both fields should be moved to the new generated tab “4. Groupon” and also add additional 4 fields (Total 6 Fields). This 6 fields should consider the following rules: Basis rules 1) The data which will fill in “Gutscheincode” and “Securitycode” fields cannot be identical. That means if the customer type the same data in both fields and click the button “continue”, then the system should be pointed out, that this both field cannot have the same data. (Error note: “Der Gutschein- und Securitycode müssen unterschiedlich sein”) 2) The customer can type in both fields only data, which is a combination of numbers (0,1,3-9) and alphabet (a,b,c … z). For example “354TEKL57Z”. If the customer types other data as numbers and alphabets, the system should give an error. (Error note: “Der Code ist leider ungültig. Der gültige Code besteht nur aus 10 alphanumerischen Zeichen“) Specific Rules by redeeming a coupon code (see attachement 3) Info: I have installed “order attributes” from Amasty. All this fields in tab “4. Groupon” can be generated by this extension. [login to view URL] Additional I have also installed the extension “Multiple Coupon” from Amasty, so it’s possible to redeem more than one coupon code. [login to view URL] 3) If the customer redeemed one coupon code successfully and this code has 10 digits, then only the following fields “1. Gutscheincode” and “1. Securitycode” in the tab “4. Groupon” are required fields. The other fields “2. Gutscheincode” and “2. Securitycode” as well as “Die übrigen Gutscheincodes” and “Die übrigen Securitycodes” are not required fields. 4) If the customer redeemed two coupon codes successfully and each code has 10 digits, then only the following fields “1. Gutscheincode” & “1. Securitycode” and “2. Gutscheincode” & “2. Securitycode” in the tab “4. Groupon” are required fields. The other fields “Die übrigen Gutscheincodes” and “Die übrigen Securitycodes” are not required fields. 5) If the customer redeemed three or more coupon codes successfully and each code has 10 digits, then all fields “1. Gutscheincode” & “1. Securitycode” and “2. Gutscheincode” & “2. Securitycode” and “Die übrigen Gutscheincodes” & “Die übrigen Securitycodes” in the tab “4. Groupon” are all required fields. The customer can type in those 4 required fields “1. Gutscheincode” & “1. Securitycode” and “2. Gutscheincode” & “2. Securitycode” only data, which is a combination of numbers and alphabet (basic rules) with exactly 10 digits for example “354TEKL57Z”. And the other two fields “Die übrigen Gutscheincodes” & “Die übrigen Securitycodes” accept at least 10 digits which is a combination of numbers and alphabet (basic rules). No restriction for more than 10 digits. 6) If the customer has not redeemed any coupon code, then no fields in the tab “4. Groupon” are required fields. 7) All fields should be displayed on the order grid. The possibility to switch on/off to display the fields at the order grid. (I have installed “order attributes” from Amasty. This extension already considers this function. Properly some adjustment are necessary) 8) This to develop extension can be switched on/off easily at the backend of Magento. Once this extension is switched off, the checkout procedure is like usually (Magento original). For more project detail information please see attachement 4 We are using Magento community Edition 1.6.0.0.