The Beverly Crusherish hairdo that Shanna sports here would be her default for the rest of the series, and yeah, there probably is some significance to the fact that she let Will decide her look.
In fact, if I had known then what I know now about storytelling I probably would've made a bigger deal about that. RIP AND TERI and THE BOURNE IDENTITY both feature disguise scenes with a clear erotic charge.
"MUD" stands for Multi-User Dungeon, Domain, or Dimension, an antecedent of today's MMORPGs. When I was in college I saw people using the acronym MUDD, for Multi-User Dungeons-and-Dragons type game, but that appears to have fallen out of favor now and it may have been a misuse anyway. (Thanks to Bo Lindbergh for the tip on that.) Fortunately for this page, MUDded and MUDDed are spelled the same in allcaps, so that's one thing you didn't know was wrong until I told you. :-)
We never got much of a sense of Thack's origins, but Tim's bit here is beautiful.