Figured I'd help you in this field:
1. Yes, you can integrate your design/template into an eCommerce store if you have knowledge of whatever language the script is written in. In example, a template can be integrated into osCommerce.
2. Now, about merchant accounts, all a merchant account is is a simple business bank account with a payment gateway with some of them. Take for example, Merchant Warehouse (
http://www.merchantwarehouse.com) --- you can get an account with them and use any of the payment gateways they offer... VeriSign, Authorize.Net, LinkPoint, etc. I recommend my opinion to Authorize.Net --- very good payment gateway.
3. Now, with your eCommerce store, you have to find out WHICH payment modules it has to offer. Let's once more use osCommerce for an example. For you to accept credit cards, you'd have to setup the Authorize.Net (upon if you CHOSE Authorize.Net as your payment gateway) and input your transaction ID and password I believe, for Authorize.Net --- your now set to go to accept credit cards.
If you want to know anything else, just post and ask, I'll help you out (literally, integrate and all that) if you want, not free but not expensive either
