Thermostat questions...dual fuel and temp sensor... Hookdog or Speadie maybe?

After reading the posts on the W TSTAT, I have some ?? My current system is a 5 yr old, Trane, dual fuel (heatpump and NG, which kicks in around temp of ~ 30 or less outside…not often), with a Honeywell TSTAT (has 4 AA batteries and a watch battery). Pics link below.

  1. does the W TSAT recognize the outdoor temp sensor to switch to NG when too cold outside for efficient heatpump operation, or ONLY when the inside temp difference between actual and set point is 10+ degrees ?

  2. is the workaround of selecting “other” as my system in the setup menu the only way to get this to work properly (with perhaps the G wire left disconnected or connected) ?

  3. any advice on how best to wire up the W TSTAT given above and the pics ?

  4. if there is a power interruption or wifi signal loss, does the W TSTAT just drop to some default heat/cooling settings ?

  5. is it possible that the W TSTAT is not really a good alternative for my system given their current hardware/software setup ?

pics here…

Thanks !