Fuse #7 and #10 in the additional fuse box powers up the power windows. It is a fuse in the permanent power circuit for the (rear and front) windows.
Power seats, power roof and additional sound systems are fused in the back as well.
That other white fuse might be for the power roof...
The clear tube that is connected to the (overflow pipe of the) battery is meant to lead possible battery water and gasses out of the trunk.
Partly due to this tube not being connected properly or at all, a lot of the C classes around here suffer some severe rust in the trunk (spare wheel well).
with a minor 600+k