First off, I'm sorry to hear you ran into some issues during your hour of consulting .
With regards to the limitations, I would check out the QuickBooks Desktop SDK Limitations and the
Something to note is that updates are usually made first to the QuickBooks program itself. This means that some features you may find available on either QuickBooks Online or QuickBooks Desktop, may be new features and are not supported by the
Intuit IPP or QuickBooks SDK. Those changes can come sometime later or may not come at all. Therefore, it is hard to keep a complete list of all limitations. We try to keep the Help Center as up-to-date as we discover them.
As for you question about the Report Designer, it will run on any version of Windows (XP, 7, 8).
Hope this helps and let me know if you have any other questions.