Regarding your issue about the image not being the right size and the colors being messed up, you'll have to read some tutorials on that stuff. Like my thread says, the images aren't indexed, so they can't be inserted into a ROM hack in their current state. Someone, or you, will need to put them through a program such as IrfanView to index them. Then, the inserting process will go just dandy. Ask around the ROM hacking section, and everyone will know what you're talking about. They can help you a lot.
And yes, I think I already told you, but my friend countryemo is right. Anyone can use those 2 sprites of Nitro now. I don't make sprites exclusively for one person....at least so far.