random questions about trademarks

If a word or phrase is trademarked in the USA,

... does that apply outside the USA (like countries that have intellectual property/copyright agreements)?
.... does that apply to variations of the spelling.  Like if the trademark is Something Color, would "Something Colour" still be covered?  

It depends on a lot of factors...

The first consideration is what you consider words of phrases. You can only trademark intellectual property, so a title to a movie or book is NOT able to be trademarked. How could it? Its something you thought of, but it is not exclusive to you. I might have thought of the same title for my book. With about 1 billion new books published every year, it would be impossible to even do a search to see if that title is being used.

But if something is intellectual property, you can have it trademarked by something called the Madrid Protocol. It is similar to copyrights in that a host of countries (108 throughout the world) banded together to say with one trademark, you are covered in 108 countries. It is a bit different though than copyright in that you have to apply for the trademark as it is not freely given to you instantaneously like copyrights, and it takes 18 months to get.

Is it worth doing?

I don't think so. As a business owner I got far more important things to do with my time then worry about a trademark I came up with. Really, is my little business going to grow so big that I must worry about a phrase or company image? Even if I grew to be important enough to care, would I have the time and money to chase down people with lawsuits if my trademark was copied? And that can only be done in 108 countries, leaving 87 countries where my trademark has no standing anyway.

I hate to be cynical on a system designed to protect, but the world is full of people who got patents, copy rights and trademarks, and despite years of litigation got nowhere defending their case. A case in point, Caterpillar Tractor Company who stole the idea of bulldozer tracks off Alvin Lombard who patented his tractor in 1900. The founder of Caterpillar (Yes THE Cat company) saw his tractor working in Wisconsin and copied it. For the rest of his life Alvin Lombard sued caterpillar but got nowhere because Cat had deep pockets and every time they lost would appeal the decision.