On fords when the glow light comes on and stays on, it is quite often an engine fault warning.
in your case I suspect it is in limp mode and very much suspect it is an EGR (exhaust gas recirculation) fault, often because they block up with oily sooty gunk, commen on older diesel's.
Or an injector fault, maybe blocked slightly, get some diesel injector cleaner from a car parts place or Halfords (whynns is a good choice)
But yes an diagnostics is most likely required.
As for the wiper issue, possibly a dodgy earth due to corrosion, again fords known for it, or its the wiper stalk playing up, would most likely need replacing.
Hope that helps
I would suspect your girlfriends issues are down to a corroded fues box on the inner wing under the bonnet on the right hand side, the c2 is known for the fues box filling with water due to badly desighned drain off when it rains, ciroen know its an issue