Project trunk has started

My trunk is rusty. 90% of this rust started after some twats from the winter-parking put it outside in the rain eventhough I asked them not to. When I picked up my car the outside was dry but there was a small puddle in the trunk and I only discovered so after I drove to the current parking. Crap!

So today I started preparing the trunk for sanding and painting. But I also wanna know what these wires are for:

?

This is what the trunk looks like right now. Too much rust...

It's still surface rust so I should be able to sand it away and paint over it.

Behind the filler-neck.

There is this soft, white, rubbery substance in the corners everywhere. I don't know what this is...

My paint also arrived today. In convenient spray-cans :-)