Replying to Internet Transactions questions +K

Hey guys, I've got a small business going online soon and had a few questions.

I need to be able to make transactions if people want to buy my stuff through the website.
I do not want paypal for a number of reasons.

I've been doing a bit of research but still found a few things unclear.

First, what is a merchant account, and do I need one?
Do I need a security company like verisign to back the transactions?
Is there a difference between a merchant and an ecommerce account?

Any help would be reeeeaaaalllyyy appreciated as I'm trying to get the ball rolling ASAP.
Mad karma to those that help, maybe some shwag. Thanks guys

-Sam