Nice start Eric.
It definately looks like you need need to apply a flat, they will also help with the vignetting. To save your files as jpegs, convert your Tiff to an 8bit image (Image>mode>8bit) and then save as jpeg. Alternatively you can use your tiff and go File>Save for Web and then adjust your size and quality then.
If you have difficulty using Reg to apply your flats, you can do it in PS by using Image>apply image select your flat and then subtract it from the original.