You should replace the line. They get brittle with age & heat. A basic fuel hose from McParts will get the job done if the MB part is too pricey or takes too long to get.

There is a dipstick attached to the fill cap of the reservoir. The fill level is ~6 inches below the top, for an unladen car. Really, as long as there is fluid in the reservoir, it will be fine.

No bleeding necessary, the system is self bleeding.

- JimY