The Innocence of Muslims film: Questions to a Muslim

Dear friend,
I have some questions prompted by the recent furore over that stupid film, which you may or may not wish to answer.

I've been looking into why Muslims should get so upset about Muhammad being insulted while the followers of other religions seem to be less sensitive.  
I visited the Islamic Q&A site you recommended on which I found the following question:
I heard on a tape that whoever insults the Prophet (peace and blessings of Allaah be upon him) should be executed even if he shows that he has repented. Should he be killed as a hadd punishment or because of kufr? If his repentance is sincere, will Allaah forgive him or will he go to Hell and his repentance will be of no avail? 
The answer starts as follows:
Praise be to Allaah.  The answer to this question may be given by addressing the two following issues: 1 – The ruling on one who insults the Prophet (peace and blessings of Allaah be upon him) The scholars are unanimously agreed that a Muslim who insults the Prophet (peace and blessings of Allaah be upon him) becomes a kaafir and an apostate who is to be executed. 
The answer continues to make references to various hadith such as:
With regard to the Sunnah, Abu Dawood (4362) narrated from ‘Ali that a Jewish woman  used to insult the Prophet (peace and blessings of Allaah be upon him) and say bad things about him, so a man strangled her until she died, and the Prophet (peace and blessings of Allaah be upon him) ruled that no blood money was due in this case. Shaykh al-Islam Ibn Taymiyah said in al-Saarim al-Maslool (1/162): This hadeeth is jayyid, and there is a corroborating report in the hadeeth of Ibn ‘Abbaas which we will quote below. This hadeeth clearly indicates that it was permissible to kill that woman because she used to insult the Prophet (peace and blessings of Allaah be upon him). Abu Dawood (4361) narrated from Ibn ‘Abbaas that a blind man had a freed concubine (umm walad) who used to insult the Prophet (peace and blessings of Allaah be upon him) and say bad things about him. He told her not to do that but she did not stop, and he rebuked her but she did not heed him. One night, when she started to say bad things about the Prophet (peace and blessings of Allaah be upon him) and insult him, he took a short sword or dagger, put it on her belly and pressed it and killed her. The following morning that was mentioned to the Messenger of Allaah (peace and blessings of Allaah be upon him). He called the people together and said, “I adjure by Allah the man who has done this action and I adjure him by my right over him that he should stand up.” The blind man stood up and said, “O Messenger of Allaah, I am the one who did it; she used to insult you and say bad things about you. I forbade her, but she did not stop, and I rebuked her, but she did not give up her habit. I have two sons like pearls from her, and she was kind to me. Last night she began to insult you and say bad things about you. So I took a dagger, put it on her belly and pressed it till I killed her.” Thereupon the Prophet (peace and blessings of Allaah be upon him) said: “Bear witness, there is no blood money due for her.”(Classed as saheeh by al-Albaani in Saheeh Abi Dawood, 3655) 

You can see that Muhammad thought the killing of a Jewish woman and a female slave of one of his followers (with whom the follower had two sons) did not require a rebuke because they had "insulted" him. As the cleric writing this says: This hadeeth clearly states that it was permissible to kill that woman because she used to insult the Prophet [...].

I therefore have three questions arising from this:
Do you think the idea (implied by this answer) that it is permissible to kill those who insult the Prophet is a commonly held belief among Muslims?
Is the arrogance and pride implied by allowing someone to kill a woman because she insulted you worthy of the "best human ever to have walked the Earth"?

I suppose I might also ask is it not inevitable, given the above and the belief in the sunnah, that Muslims will commit atrocities such as the murder of the American Ambassador? 

Now look at this from the same answer:

It may be noted from this that the Prophet (peace and blessings of Allaah be upon him) had the right to kill whoever insulted him and spoke harshly to him, and that included both Muslims and kaafirs. 

Why if, as we are constantly being told, the religion of Islam is not violent, instead of labouring the fact that Muhammad had the right to kill those who spoke harshly to him, doesn't the cleric say that killing anyone for a perceived insult is abhorrent and uncivilised?

Do you believe that your Prophet "had the right to kill whoever insulted him and spoke harshly to him, and that included both Muslims and kaafirs"?

Is it any wonder that those in the West who are beginning to research Islam in depth feel that the claim that it is a "religion of peace" rings increasingly hollow?