What is this hose to? What does it do?
 

Today it purged a lot of red fluid on the driveway after driving 20 miles in 94F weather

The part that connects to something was LOOSE and spraying all inside the engine compartment.

2 questions I guess:

What is it connected to, and what's it's function?

http://s4.postimage.org/vgcywzjga/DSCN9584.jpg

http://s4.postimage.org/dqb5dc4e2/DSCN9579.jpg

http://s4.postimage.org/h9x4qojlm/DSCN9580.jpg

http://s4.postimage.org/od51tu1iy/DSCN9583.jpg

Also, it might not be the cause because as you can see in the last picture, there is liquid in places that would not be from a loose purge hose (if that's what that hose is)

Any diagnoses welcome...

I would say hose is unrelated as its an overflow line for your overflow tank haha. and your tranny fluid is leaking where line it connects to rad? the white plastic ring is just a 'shield' or whatever you want to call it, you can pull it back to have a better look

Yeah, I took a closer look and it was leaking alright...

The shop is the one who put the new radiator in.

They must have done this on purpose so the transmission fluid drains and ****s the tranny up...what a surprise.

Now I'm going to have them clean all this mess up and tighten it correctly.

so does anyone know how to tighten in so it stops leaking?

http://s1.postimage.org/cvftrb5hk/DSCN95762.jpg

that is quick disconnect fitting you have to get a new one, most likely they cut the oring inside the fitting, they sell them at any auto parts store. with a new radiator it should have come with the new fittings installed already so it should be tight, but you can check by turning the nut.
https://www.napaonline.com/Catalog/C...+50014+2014003

It looks like it is a new fitting. Pull the plastic ring back and remove the small C-clip that holds the line in. Then you can pull the line out. It most likely got a little grain of dirt in there or something. Wipe the line and the fitting of really good. Then push the line back in, put the clip in and slide the plastic ring back over the fitting. If that doesnt fix it you will probably need a new fitting.

Well I tightened the bolt a little bit.

That seemed to really help.

I barely noticed any red liquid coming out.

We started the engine and let it warm up.

Still nothing.

Before it was a lot worse.

Either they never tightened it properly or it just came loose from the cold/heat.

Going to keep an eye on it.

How risky is it to keep the skid plate off?

you can keep it off as long as you dont go off the street

I just did my rad and it came with new fittings but I had to install them, possible they didn't tighten it enough(hopefully you fixed the issue with tightening it, could have also been a piece of grit and by turning the line in the seal it sealed it)

the bottem line on mine was difficult to line up and click in.