By purchasing a HQ downloads pack you obtain the ability word art images in high quality (HQ) PNG and vector EPS or SVG formats which can be used commercially without attribution to WordArt.com. All other features (fonts, shapes, etc.) are the same in paid and free accounts.
No, all successive downloads of a same image even in different formats are not counted.
No you can't. If you wish to use a word art image commercially you will need to purchase one of the HQ download packs and download the image in HQ format.
Yes, you can resell the images to your clients that were downloaded in HQ formats. You can't resell SQ images.
You can sell the images downloaded in HQ under any pricing plan on stock image sites. But you can't sell free SQ images.