Perhaps you should try that European processor, Verotel. They are the processors for most of that questionable material from Russian and other sites.

Another idea would be to tone down your site at first. Once you get an account, customers, etc... then slowly introduce your "questionable" images.

I would suggest that the site be a paysite. That would open a huge market for you. Selling downloadable images per unit isn't the way to go. I wouldn't pay for them unless they were signed limited edition litographs, pen/ink, etc... That would make them collectable items of art.