How can I make Pages my default WP program?

If you want pages to open all .doc files do this:

Find a .doc file. Right click. Select get info. In open with box choose pages. Select change all.

How can I make Pages my default word processing program?

Press and hold the Apple Pages icon in the Applications folder, then drag the Apple Pages icon to the Dock and drop it in the desired position. This lets you make Apple Pages the default in the sense of being the simplest to start. If you want .DOC format to open in Apple Pages, you can choose to make Apple Pages the default for file format .DOC. Not knowing what you want, it might make sense if you specified your aim, though.

/hh