Double check your Login ID, and Transaction Key - and I have Enable Authorize.net Credit Card SIM, True
Also, have you set up yor MD5 Hash?
I have my orders still set to Pending - but thats basically it, all my other information is as yours is.
My payments are working fine, and going through, EXCEPT, when it redirects them to my checkoutsuccess.php I get the broken images (see other thread about it)
The only thing I am thinking, was when I set mine up, I never went into "test mode" @ Authorize.net - I just made a product cost $1.00 and added 5 cents shipping and gave it a few shots on my credit card, then voided them in the a.net control panel.