Dota betting question

[Admiral_C]

Hey, have 2 question about betting in Dota both related to BO2 type matches 

1) match odds (3-way) what does it mean in a bo2 game. What happens if I bet on Team A or on a Tie.

2) both teams to destroy a barracks (ranged or melee). Am I right that it means that both teams need to destroy at least 1 barracks (any type)? 
 

thanks!