EPS is an Encapsulated Post Script file that is pretty much associated with vector programs more than Photoshop. 

you CAN open the file in photoshop if you wanted, (i usually just drag the EPS icon over my PS icon on the dock) you get a prompt asking a few things (don't have a screen grab to toss up...) but what you should know is the most important thing to consider is the size. Vector objects are scalable, and this means that you can resize them at your pleasure (make them smaller and then enlarge them) without lose quality. But when you open a vector file in Photoshop, the vector image will be turned into a raster image. So you won’t be able to resize them in according with your needs – you can make it smaller, but if you try to enlarge it the result won’t be so good…

This is why I suggest you to choose a very large size and then make them into a "smart object" - Smart Objects will retain the ability to scale (up AND down) without losing quality!

 

(this is mostly babbling information - useful to some-ignored by others)

retrocity