A couple of WTF? Questions

[72tutone]

A few pics here.
In the first one, I removed my bed over the weekend and this looks like a brace/cushion? I only have one of them on the bed
The second is a rubber hose/line going to the rearend. What is this for? Its not hooked to anything
And the third and final question, is I dont know what is in between the trailing arms? It feels like metal but I'm not sure. I only have a 110 welder hooked up with gas. Can I take out whats in them and stitch them together? I have searched and numerous folks have done them, although I dont know if they did them with a 220 or if a 110 is enough.

Thanks!