1. This isn't a site in the way you're thinking--the forums are driven using commercial software. The makers sell an add-on product for mobile users, but it's expensive and a known problem in terms of security.
2. You can zoom in on the text.
3. Actually, the font setting is larger than most sites, not smaller, since it isn't fixed in terms of point sizes.
4. I'm visually disabled, and manage on my iPhone.
5. iOS 5 changes the way fonts are rendered; any changes we make now will be a problem in the fall.