Those errors are not that complex actually. Most of the issues arise from the source of your file, GIGO. I assume there are attributes within the tags instead of a stylesheet. Remove the attributes or use the stylesheet. The latter is always the better option.
If you have <u> in your document (aka underline), than that is only allowed within <p> or <div> tags (ok, also tables but lets ignore that). Apparently somewhere in your source it is in another tag.