A few Newbie Questions:
When a monster also has a “threat†when do you resolve that? Does the Defender get a chance to Respond (i.e. get rid of the monster) before it takes effect?
Once you play an attachment can you discard just the attachment in your discard phase?
Other than the unusual movement fight does the movement on the monsters serve any purpose? I can't see how they ever move or go through trap or locks?
If the threat is a special effect, not a hit effect, it is resolved first before combat. For example all Demons have the effect "When attacking opponent must overcome Threat..." This is resolved first, then you go into combat.
Only if the attachment is a Treasure card.
Monsters don't move, they are played into a space then generally go into your Pack after combat. The Speed score is listed in order to complete their stat block. It is used with some of the optional rules available on the Atlas-Games Dungeoneer site. (There is an important mechanic in an upcoming set that really utilizes the Speed score)