I like tips #2, #5, #6, #8 and #9 and think they're probably the most important for Google and any other search engine.
As for the <h1> debate, it's true you can have as many <h1> tags as you want, but it's also true you can style your text with old <font> tags, but this is not the way the modern standards are necessarily meant to be used.
The <h1> tag is really meant to be a single header about the main purpose of that particular page. Then, you can break into sub categories, or <h2> as many times as necessary. Then, if you have subs for each <h2> tag, you can use <h3>, <h4>, etc...
For my site, I already have an <h1> tag on every page, so using that technique with an <h2> tag would probably be just as useful.
You should also look into creating a sitemap of all the links in your site using .xml (for Google), .txt (for Yahoo) and .html for the rest of of visiting your site. I know there are a lot of other search engines, but I'm confident that if you follow the rules outlined and DO optimize your page for these 2 big search engines, most of the other engines will pick you up too. If not, there's not much else you can do unless you want to start breaking rules.
Check out these links if you're interested:Google Webmaster TipsYahoo Sitemap SubmissionsGeneral Sitemap Info for many engines
Hope this helps, and oh yeah, thanks for helping me make my discussion board more search friendly and standards compliant!