Customize Magento payment module

Hello. I have basic template of magento payment module. Now it is using to collect credit card data in the checkout, sending to the gateway and process the response. I need modifications for it. 1. check if SHA1 hash function is working (i am not sure if it is correct) 2. add additional iframe redirect if it is manual mode of payment (customer will not enter data on shop but on gateway over iframe) - does not know how to handle different methods in different controllers 3. divide the response to two different static url's - one for success and one for failure - as for now I have all response handling in one method controller. I need fast start and development. After this is done some specific questions still will be needed but later on I can handle it by myself. All posting and response codes can be handle by me as well as real testing and implementation on my site. No access to site what so ever.