1) Yes, it is a Wilhag (which stood for its founder's name Wilhelm Hagenkamp). One point for that.
2) I found this picture just labeled as Wilhag and I went through my book shelf and found a book about excavators where two similar looking Wilhag truck-based excavators were pictured, with "Wilhag" logo at the radiator and a caption that those chassis were built by Wilhag themselves. But you certainly are right with your Kaelble identification and there were quite a lot Wilhag cranes on Kaelble chassis. So there is another point for you. Well done!