1. i like to know how i can change front page scrolling banner
Scrolling banner consists of HTML that can be edited in Design -> Banner Manager. Look for Main Banners
2. want to add custom payment method like "credit card swap" after selecting this method the customer will get 2% additional charges in total checkout amount.
There are no ability to add custom payment methods without creating new extension. You can use authorize.net payment to use credit cards. For discount, you probably need to get promotion extension on extensions store.
3. the brand scrolling banner @ the bottom of my page is not working. means cant see anything, only blank box is there.
Probably not set correctly. Check all banners and make sure they are enabled.
4. is it possible to add different "static banner" on different pages.
Yes. You need to add banner, create block with the banner and add block on the page you need in layout section.
You can skip step with creating banner and just create HTML block.
5. how can i add "similar product" pan.
This is related products. Look under product edit and relations tab.