categories and php

Hi- i wonder if someone can help me out. In my site i use some php to identify the current page for my navigatiomay bar.
<?php $thisPage=”Music”; ?>
ive decided to move all of my site into wordpress and would like to know how i can use the above code with the categories.. something like:
<?php $thisPage=”music category”; ?>
can someone point me toward something?
also, while im asking- does anyone have an opinion on wether or not it’s a good or bad idea to use wordpress for all of my sites content? should it be used primarily for the journal pages?
i have heard its not good to tax the db too much, but would like all of my content to be searchable and have rss feeds.
any ideas?
thank you