Based on press photos, the snowtown sledding task is a route info at the beginning of the leg. Detour is Water Wheel (I'm assuming build a functioning water wheel system and then collect water from it) vs Water Boat (rowing a basket boat to pick up and deliver items), and the roadblock is driving a scooter type thing through a testing course.
Chris and Bret's speed bump is making snowballs at snowtown, the same place as the sledding route info
For the timeline
Teams doing the Water Wheel challenge: Rachel/Elissa, Leo/Jamal
Teams doing the Water Boat challenge: Janelle/Britney, Chris/Bret, Eliza/Corinne, Tyler/Korey, Becca/Floyd, Colin/Christie, Nicole/Victor
People doing the roadblock: Janelle, Eliza, Korey, Jamal, Elissa, Victor (the rest is TBD on the show)