I have successfully used the test account and integrated Authorize.net, but when I go live, is there any sort of certification that needs to be done or am I good to go live?
No. But if you do certify your software you can get it listed in the certified solution directory and advertise it as such which is a good thing.
Also, do I need to tell customers to obtain their own API Login and Key that they will use?
Yes. But generally whomever is establishing their merchant account or otherwise pushing your solution will be handling this.
Is this something a regular merchant applies for, or is it given out in their account information and they can quickly plug it into my software?
Yes. Acquiring an Authorize.Net account is fairly simple to do once a merchant account is established and plugging live credentials into your software will be no different then adding the test account data as it literally is not different in any way other then the live server URL being different of course. So if your software is well written setting it up should be a breeze to do.
