Thankyou for saying this Dean! Keyword meta tags are all but useless. Stick in a few misspellings and be done with it.
For SEO purposes, write unique, keyword rich <title> tags for each page of the site. For better clickthroughs in the SERPs, write unique, compelling meta descriptions for each page of the site.
As for dynamically generated pages? The search engines generally index them just fine and you should be able to optimize them like any other static page. The problem comes in when there are too many parameters in the query string (which I think has been mentioned here already).
There are usually workarounds for this although I can`t speak directly to the CMS you are using.
Many many sites are dynamically created now and search engines recognize this. They just ask that the URLs be as "search engine friendly" as possible.
A nice ditty on the subject: