Domain name variations...copyright infringement?

Is your brand trademarked? That's probably going to be the deciding factor in what you can and can't do.

Do you have a registered copyright or trademark for that name?

copyright infringement no

trademark infringement maybe did you register the trademark

what do you mean same exact content? is that content that you created?

You copyright your work (Photos, text)
You trademark you Name and logo.

Without a trademark, you dont have any chance.......

If youre going to build a domain into something big, ALWAYS protect your brand by registering possible mistypes and beat your competitors in that game as well as avoiding possible legal hassles.

like most said, sounds like trademark, not copyright

and you don't HAVE to have it registered to claim it, but without registration most companies (registrars for example) aren't gonna do much if anything

I think previous responses have been somewhat accurate in pointing out that this is a matter of TradeMark rather than Copyright. However It is entirely not true that you had to register a trademark to be protected you can claim trademark based on evidence, although it always helps if you have had something registered. The real challenge is proving that variation of your name is violation of trademark and this is not as easy When it comes to domain names, the issue becomes a bit more complex, for instance Sonny electronics is a well known brand and then we have SUNNY ELECTRONICS http://www .sunnyelectronics.com.au/ there is website tooorgle .com a torrent search engine that mimics google. Furthermore there is the issue of TLD, even if you have a registered trademark and you can prove that the use of other domain constitutes trademark abuse, The Territory of the Trademark is a question in itself, is your trademark protected in Russia (.RU domain) China(cn domain) ?etc.
As to providing similar content, unless the other website is providing the exact copy or product built off your secret/patented design, it wont constitute IP violation as you cant protect an Idea.
As to sending C&D notices, you can, if you wish to go to court, as you can use it as an evidence that you went down all avenues and it wouldn't work. However should they prove you wrong that is an evidence that you were wrongfully accusing someone of something they did not do.
I am sorry if this post does not help you directly but I felt it might be beneficial to give you the full picture.