Help with merchant account/gateway?

My site will be ready to go live within the next few weeks, so I was looking into the merchant accounts but I was a bit confused. I'm unsure what to do or where to go or how to implement this with the cart.

I just clicked on the cardservice international link from this site and filled out the application since they said no setup fee, etc. that I saw authorize.net charges. So now what? Do I also need to setup an account with a gateway? I'm assuming here that cardservice intl was the merchant acct? Do I have to pay the merchant acct people a % plus a cents per transcation AND pay the payment gateway people as well? Who is the actual gateway?

So, then once I get setup with these, how do I tell Zen-cart to be able to go through my account? Will I get an account number, username, etc. that I have to put somewhere in my cart?

As you can see, I'm a bit confused with the process of being able to take credit cards. Can someone please explain this to me? Thanks!

http://www.merchantseek.com/merchant_accounts.htm

Thanks for that link, which did provide some information on merchant accounts, however it didnt answer all my questions.

1. Once I setup my merchant acct, where do I go for the gateway? And do I have to pay fees to both? Seems like any profit made from products would be eaten away by the percentages plus transaction fees it seems that are due. :dontgetit

2. How do these services fit into Zencart? Do I have to add a module or something to make it work?

3. Which services does Zencart work with. I understand that only some companies are compatible with Zen? Before I continue to setup the account with Cardservice Intl and whatever gateway, I need to make sure they will work with Zen first.

Any other info I need to know? Or can someone help me with these questions? Any recommendations or reviews on merchant accounts or gateways that are good to work with, cheap, easy, etc.? :cool: Thanks!

Yes Card Services International works with Zen Cart using the built in linkpoint module