Why was Radl afraid of Himmler?
During his meeting with Himmler he was obviously nervous. He was a decorated Colonel. What did he have to fear?
We got a job.
What kind?
...The Forever Kind.
Himmler was probably second only to Hitler. Radl's nervousness most likely relates to Adm. Cannaris' remarks about Hitler and being tied to the admiral, and any threat to his own family. Himmler could make you disappear on a whim. Even colonel's are wary of a powerful psychotic, who can make friends and family disappear at the snap of a finger.
Fortunately, Ah keep mah feathers numbered for just such an emergency!