So I went forward with the Ecobee install this afternoon. I had to check a few things with
@Anathollo to confirm my theory on the wires/ ports was correct. I swapped the Honeywell out, the Ecobee in, and had no power. I checked a few things and decided to back out of the install since it was 10p at night and already 75 degrees in the house.
Then the Honeywell was not working either. So after 30 minutes of troubleshooting and trying to reset the air handler I found the blown 3 amp fuse. The fuse is swapped and house is starting to cool down again. Will try the Ecobee again at a later time.