I did a search but could not find an answer. I create a lot, actually most of my websites using CSS.Now that I'm using more pure CSS for my sites, they don't seem to be getting indexed as much or ranked as high as the pages I created the old fashioned way with tables.
How much does CSS actually affect my SEO and how should I develop the site if so. Should I embed the CSS into the page, create the styles in-line, or link a stylesheet? I create header tags in CSS because html header tags are as controllable as Britney Spear's attitude.
Yes, CSS can impact your website's performance in the search engines, but not with regard to any of the issues you list. Generally speaking, CSS will only affect your rankings if they interpret it as an attempt to manipulate the results by doing things like hiding content from users so that only search engines would see it. The resulting page layout can also have an effect, but that's a subject that really belongs in the Search Engines topic.
Whether the CSS is contained in an external stylesheet file, the <head> section of the document, or embedded inline in your HTML tags doesn't matter at all. CSS has been with us for nearly 15 years now. If your websites aren't performing as well as they had in the past, it's not because of CSS. It's because the search engines' ranking methods have changed and the level of competition has exploded. Good luck!
Don't use display:none for any content you want the search engines to pick up on. Often it's used in conjunction with other styling to show and hide on rollovers and stuff. So the argument goes - as far as search engine indexing is concerned, like Britney Spears popularity, it will disappear.