Missing this tube on the coolant tank, is it important? can't find ANYTHING researching it, no diagrams showing it's purpose or anything, is it important?

 

That's where excess pressure is released when necessary, the tube makes a 90 degree turn down the side of the overflow tank and ends there. It's just open. Not suuuuper important but one thing you don't want is steam/coolant on the electrical connectors below the overflow tank.

 

Its not super important but you should replace it. Possible it will leak coolant onto electrical connections if you leave it like that. Considering it should cost less than $1 to fix, you should go for it. All you need is a simple, heat resistant rubber tube to fit, but make sure it's long enough so you can lead it down past the power steering wires.

 

Get a longer piece of line and run it down by the undertray...

 

and it might have dropped down but is still on the car...