New to ssl and e-comm

I'm just now getting my feet wet with a non PayPal etc.. based e-comm setup. I have been writing PHP for MySQL for about three years and Im pretty well informed of standard secure coding practises, input validation, variable declaration etc...

The projects at hand would be really low volume sales so we are looking at using the SSL cert that is provided for free thru my host co.s shared serving environment. You know what I mean, you access your files thru a rather lenghty https path.

The host co. A quite reputable one that is, assures me that it is as seccure as the one you pay for and I assume is associated with your own IP. They tell me the only difference is the path. What are your opinions on a shared cert like this?



question2:
I plan on using authorize.nets gateway to handle processing. As long as all transactions are sent using ssl and I am using good coding practises are there any other things I should be condsidering?