Search Engine Spiders forum discussing how to know which search engines are visiting your site by identifying their spiders. Share their IPs and spidering habits, and plan for them to get better SEO results.
Errm, no, Meta Tags are practically ignored by the main search engines (google/yahoo/msn).
If by "code" the mean ASP/PHP/JSP..so on, it makes no difference, search engines can't read server-side scripts, like your browser they just see the HTML and Text, they don't even care about the CSS.
Make a site with good readable content, content is all search engines care about.