What do you do more often? Apply an existing style? Or create a new one?

Obviously -- the former.

So why, after you've selected an existing style in the Format:Style
dialogue, is the default command (invoked on ENTER) "New" instead of "Apply"
? (I'm talking about Word 2003.)

Moreover, why, when you do choose "New" (deliberately or inadvertently), is
the new style always "based on" NORMAL instead of the style you've just
highlighted??

Still further: why is it HARDER to highlight an existing style than it was
in 2000? Say you have a style called "quote." In 2000, if that's the only
one that starts with "q", then "quote" gets highlighted as soon as you type
"q". 2003, however, acts dumb, pretending not to know what style starting
with "q" you mean, so you have to follow "q" with down-arrow.