I'm interested in your thoughts here.

Concerning a): I think there are very very few cases where calling someone a "loser" is a good choice of words -- I agree that Hawking's comment is most likely one of the cases where it is not a good choice of words. I would say that Hawking is most well known for things other than his speaking abilities ;).

Concerning b): Could you mention what some legitimate reasons would be? For bragging purposes I find it nearly entirely pointless in most cases, mostly due to the fact that there's a very good chance the person doesn't know what they are actually saying by referring to their IQ. The fact that the questions, "what is intelligence?" and "what does it consist of?" are such highly researched and debated topics with many established (and sometimes conflicting) viewpoints brings me to this particular viewpoint.

In actuality, personally I find it more than worthless in most cases -- and perhaps damaging -- which is what Hawking may have been referring to as well. Carol Dweck's research shows that a belief in a fixed intelligence has massive negative repercussions in many parts of life. One's IQ is often seen as a "fixed" number in the mind of a person and hence feels that it destines them to a state of inferiority to the individuals with higher IQs. Firstly it is just not true that "intelligence" (in most definitions) is fixed, and secondly, empirically it is just not true that a person with a lower IQ is capable of less (ie. is inferior, or practically is destined to accomplish less) to a person with a higher IQ.