Using Pages for Graphic Design...Options

First, let me say, I'm aware there are other, and perhaps better, applications for creating print ready and web ready posters and brochures. For the moment, I'd like to use Pages.

I've created several grade school related posters and brochures. At this point, most of the work has been viewed only through the web. Now, another project is requested, one that is web ready and print ready. I use the templates from Pages, and have purchased almost every package of templates by other vendors...however....I still would like to change and manipulate the templates once I chose them.

How can I add artwork? I know I can add certain files because I have done it. I am wondering, can someone point me to link or offer an explanation as to what type of formats/files can be used with Pages? I know with PSE there are a number of choices including png.

I am a parent volunteer, interested in taking the work to the next level. Any help is appreciated.