When it comes to title tags it's a good idea not to repeat them on all of the pages of your website. The title tags are the search engine's first glimpse of your pages and if they all have the same title tag then the search engines may only index one, thinking that all the pages are the same. So vary your title tags up and make them pertinent to the pages they're on as well as your site overall.
When a search engine visits your site they are looking for a number of things. Some of those things are your tags: meta-tags, title tags, etc. But the most important text on each of your web pages is your title tag.
The fact that the search engines include your title tag in their results should be enough to clue you in to how important they are.
Read this article: All about title tags
You should always put your keywords in your title tags. It's very important to write your website for your human visitors but you also have to cater to robots sent by the search engines.
If your keyword are in your title tags then Google and the other search engines shouldn't have any trouble finding and indexing your site's keywords. This is one of the basic things you can do to help your chances in the search engine results.