I am not totally sure what the purpose of those EVAP lines are for either, but I believe it has to do with a filter system to keep the air clean, which should be where the line connects to a green nipple.
The others I think are responsible for keeping moisture out of the air system, at least that is what I faintly remember from when I looked up info on this when I found all three of those lines disintegrating on my PA.
Considering the old units lines were disintegrated, it makes sense that this is what they were for, especially seeing the rust.
I don't think those lines let any air leak out, I am pretty sure there is some kind of diaphragm in place in the system somewhere, I say this because not only were mine disintegrated, one was disconnected/dangling, and my shocks were not loosing pressure.
My pump does seem to run more than necessary though, which I believe has to do with the systems level sensor attached to the rear control arm, as I replaced my shocks thinking this would stop my pump from continuously running, but it did not, however when I lift up a tad on the rear on that right side, the pump shuts off.
I need to figure out how to adjust that, as I am almost positive I do not have any actual leaks.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA