2 O2s, EGR, & DPFE should be around $200. Doubt all of them went bad at the same time though. Also they are easy very simple DIY jobs.
The coolant reservoir has a level sensor not a float. Simple fix is running the coolant level 1/4-1/2 inch over the max level. The hyperactive sensor is a known problem.
The other fix is to pull the sensor and clean the tip as it gets deposit buildup on it using the old green coolant. It's much less common to actually have enough build up to throw the sensor off.
I'd push the dealer to come up with the harness. It's Very expensive if they decide not to cover it (which has happened to some folks)
Good luck and welcome...
