What are the primary sources of humor in this story? Does it use verbal irony, dramatic irony, irony of situation, or a combination of all three? What particular characteristics make Kugelmass a suitable comic protagonist?
Verbal irony and dramatic irony are especially prevelant--his character is always saying things the reader doesn't expect to help promote his very Jewish persona. Perhaps the best example of dramatic irony is the point at which the machine explodes and traps Kugelmass in a Spanish textbook being chases around by the "hairy" verb "tener"= "to have". Just as K. is determined to have an affair with Madame Bovary, the verb is determined to have him.
Kugelmass couldn't be more Jewish. From the stereotypical physical description to the cultural references to food, sayings. It is funny because he also realizes the obvious stereotype which he represents and seems to be poking fun at himself. It's like going to the comedy show and having the overweight female making jokes in reference to obese people and female issues.
Particularly effective plot twists include the machine's malfunctions (the vehicle which provides him an 'out' actually traps him). Madame Bovary becomes trapped in Kugelmass' world and becomes quite the pain in the neck. This is also an example of irony as no one would expect the object of desire to cause as much pain and anxiety as the object(s) in his hum-drum life from which Kugelmass is running when he seeks the affair in the first place.
The ending is also particularly effective. It is laugh out loud funny to imagine him running for his life from the hairy verb "to have".