Can I change the color of text hotspots, and/or remove the underscore?
Yes on both counts. To change the color, prefix the hidden text (context string) with an asterisk (* also as hidden text). The hotspot will take the color of the hotspot text. To remove both the color and the underscore, prefix the hidden text with a percent sign (%, also hidden text). Again, the hotspot will take the color of the text. E.g., hotspot*context_string appears as a red, underlined hotspot in the compiled help.