I'm not directly debating any member's 2 cents, but I base my online strategy on these few articles:
Go Daddy actually has a ton of articles that explain this stuff pretty well. I go off what the Number 1 hosting provider says about SEO.
As for descriptions, yes you need a new description on every page. Back to the photo I posted with my website listing on Google, each page on my site has a title tag (Menu, Gallery, Pre-designed etc) and under each title is a unique description for that page. It's very important to be descriptive and unique.
This is really only the tip of the iceberg - there is so much you need to make sure you have in your website! I actually highly recommend just purchasing Go Daddy's SEO tool to help you fix broken stuff, make sure you pictures load OK, make sure all your tags and descriptions are good and so on.