One last thing - since Tallarn will have a couple of 8th level monks, make sure to give him an opportunity to use his slow fall and leap of the clouds abilities. Be silly to have an adventure designed for monks and not play up to their funky abilities, after all!
DMG (pg 80) has a list of poisons you could use (on shuriken). the base save for a monk of 8th level is +6, so with a decent Con will be at least a +8, so you could get away with any poison listed (up to DC 20)
