doesn't matter much if u r going for a forum site ........ but might matter if u have a pretty big site ... with loads have different types of sections ! Hope i am right ! .... i am a newbie too ! .... LOLZ
It depends. Do you want Google to have an easier time crawling your site? If so, add a sitemap. If you don't care, don't bother.
cool (I made one as per your instructions ... now I just have to give it to google... thanks everyone!
I have mine created automatically by using a plugin for my CMS. This is very convenient and I have seen that Google seems to have it easier to navigate my site. I cannot really say if it improved rankings, but it didn't hurt. If you update content regulary, I would advice you get one of those Sitemap generators going.
If you update your page content daily. Try for dynamic xml creation tool. Very easy and can be configured by cron jobs.
Daily is an option as long as you have new content on it and you are only pinging them once/day or so. If you ping often and never have the new content, it's not looked upon very well. CMS plugins work well for sites that are based on a single CMS with no additional pages, but many sites use several software packages or a hybrid with 'normal' free-standing pages as well. This is where a crawler really comes in handy. It can see your site as it is and not through the backend of how it 'should' be laid out.
The Idea of having sitemaps, is only to help google know what you have, I have seen better results with few sitemap pages which point to other articles, like category link pointing to items in it. Instead of submiting every new page. After all google these days isnt as good as it was earlier, yet 80% of traffic comes from google.
Its only for G's bot to know what you have, getting indexed is not certain. It all depends on your backlinks.