[JKT]

The version of WebKit that OmniWeb is based on is newer than the one in the current version of Safari and it has some regressions in the way it handles some things. For your second point - try identifying OmniWeb as Safari rather than Firefox and it will behave the same way as Safari does - no rich text formatting controls at all. Conversely, if you identify Safari as Firefox it will probably exhibit the same semi-implementation of rich text formatting controls etc as OmniWeb (assuming that the version of WebKit it uses is current enough... I haven't tried it myself, but the equivalent WebKit build as the one OmniWeb uses does).