How do you format text in Mathematica?

For instance, if I want to underline a specific expression or hyperlink part of the text, I split the string in multiple parts, format them separately and present everything in a Row or Column. This is not satisfactory, as one can see in the attached notebook, when I use Row for the first list there, it won't look like a proper, continuous sentence. Is there a better way to do that?

Also, in the notebook, the second output contains some patched strings. Why do I get an error when I try to export that as an HTML? (Why isn't it possible to export in .doc?)

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