Establish a style sheet for your site, so that your pages are consistent in using a particular font and point size for headings, subheads, navigation bars, etc. This consistency helps users know they're still in the same web site, even if page design varies. Some browsers cannot display all fonts and older browsers display type based on preferences set by the user. In addition, Macintosh and Windows operating systems may display a single font differently. Don't count on fancy typefaces to display properly.
Visual contrast is important for the human brain to comprehend written material.
The same goes for too much bold type. Unless you use graphic spacing between every single line of your text, the space between lines can't be adjusted. Experiment with different sizes and make sure your text is easy to read. You can use graphics for headlines to introduce more variety into your text. The tradeoff for this flexibility is a longer download time for images, so keep your total file size in mind and use images for text just when you really need them.