No, all successive downloads of a same image even in different formats are not counted. Please take into account that once you re-visualize your word art it will be considered as another image and will be counted if you download it in HQ format.
After purchasing a HQ downloads pack you will be able to download your word art images in high quality (HQ) formats. HQ images can be used commercially without attribution to WordArt.com. You will be able to download in raster PNG / JPEG and vector PDF / SVG formats. All other features (fonts, shapes, etc.) are the same in paid and free accounts.
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.