This is a WordPress plugin that allows you to use Smart App Banners, introduced in iOS 6, with your WordPress blog.
It's only available on iOS6 devices. if you want to check that it's working and you don't have a device, you can "View Source" on your page and look for the text "apple-itunes-app".
Where did you put the App ID? Or in the App ID field or in the "App ID (iPad)" field?
If you only have one app -- iPad-only or Universal -- you only need to specify the "App ID." The "App ID (iPad)" field is for when you have two apps of the same name, one for the iPhone and one for the iPad. You should put the default (iPhone) ID in the top field and the iPad App ID in the other one.
The quickest way is to see if you can fix it yourself. I accept patches! But if you can't, please let me know and I'll see what I can do.
I accept patches! I'm also happy to hear your suggestions but I can't promise anything.
Probably not. But since I always keep my installations up to date I have no way of testing on older versions. I believe it should work going back all the way to 1.5.1, but I've not tried. Let me know if you get it working.
You can always buy my apps. Have a look at http://www.wandlesoftware.com/. Or there's a donate link at the same site. Or if you can write code, I accept good patches.