1) i guess using tags helps! install the plugin auto-tags, set it 5-5 (you will see what i mean when it's up) and you're good. you don't have to worry about the tags anymore, and it kinda helps you with the seo.
2) here's what i do. i use my main keyword in every 2nd title and use the keyword in every single description. also, you can add other keywords to the text! I always stay at minimum 50 words for each post. if you ask me, a 100-110 description is enough and it will totally boost your seo.
also, make sure to add the tags widget to the main page, since it will totally boost your rankings. <- my own experience.
make sure to add your site/sitemap to google webmasters tool
3) never used forums before, but if you ask me, i would let google find it!
hope this helps.