I figured out a few more things.

1. The gps ekf node is creating the map->odom frame. It is also supposed to be creating the map->utm frame but I am not seeing it. That might be because nothing is connected to utm so it does not publish.
2. I changed the global costmap params to use the map transform for its global frame. If I am right then when I give the nav stack utm coordinate it will transform them correctly.