I've been following the situation in Haiti via Democracy now and they have covered this topic extensively on their daily newscast. They even flew some reporters there for a few days. I highly recommend to subscribe to their tv/radio podcast (is free). I also recommend to read Naomi Klein's "The Shock Doctrine" for a good background on disaster relief operations.
My conclusion is that the whole violence situation has been fabricated. For example, the prison escape that you mention, they had an interview with a local civil rights activist who said that about 80% of the prisoners where in prison without charges. Political prisoners of the coup regime are being held for years without trial. According to him the case could be made that the mass escape had actually been a good thing.
Everybody interviewed during the first days were saying that there was no insecurity problem. There was no need for massive deployment of soldiers. The guy in charge of the main hospital n Port-au-Prince was even complaining that the arrival of troops had interfered with the functioning of the hospital.
Tons of help has been shipped there but almost none has arrived to the people. Lots of volunteer nurses and doctors have arrived but they don't have access to any electricity or medical supplies. They are doing tabletotop amputations with tools acquired at the local hardware store and without anesthesia. Most of which unnecessary as they would have been avoided if they had had antibiotics on the first place.
The USA controls the airport and are preventing some of the planes with aid to land. Tons of aid has arrived but is just staying at the airport, or being delivered to ... the USA embassy. The little aid that is being delivered is being handed out by armed personnel who have been told the people out there are dangerous and they throw them food from a distance. People are getting really pissed of at being treated like dogs and/or very frustrated of not receiving any help.
It's the perfect recipe for violence and has been perfectly executed according to a plan. And it is starting to work: there are the first reports of insecurity at night, women being raped. Communities are just asking for proper lightening at night in their camps site to prevent this from happening. Nobody wants guns.
Local communities had all the experience required to get organized, and all the means except petrol. If they had just been handed some gas they would have used their own trucks to get water for the victims and relocate the people to less hit areas.
As usual when there is a natural disaster the disaster capitalists have stepped in to size the opportunity to steal as much as possible from the local people (they call it privatization). It is crucial that local communities are prevented from self organizing. There is also the issue of preventing any good PR from "hostile" regimes: cuba had already 400 doctors in the ground when the earthquake struck, and they sent more help immediately, Venezuela also sent aid, so did China while the USA was still "planning". In their military effort to prevent good PR for other governments they missed a golden opportunity to create good PR for the USA: the Guantanamo base is just around the corner and they could have sent emergency aid from there during the first hours. They didn't.
There is also the issue of racism. With Haiti being the first and only independent state created by a slave revolution, it is even more pressing to keep them poor, otherwise they would set a bad precedent. God forbid people from realizing that a bunch of negroes are capable of running a country. The USA has recently done two cups against a democratically elected government in Haiti (both times led by Jean-Bertrand Aristide) and it has had very good reasons to do so.
Here is a sample of democracy now reporting:
Security “Red Zones” in Haiti Preventing Large Aid Groups from Effectively Distributing Aid
As thousands of well-equipped US soldiers pour into Haiti, there is an increasing concern about the militarization of the country, supporting the soldiers and not the people. Or, as one doctor put it, “people need gauze, not guns.” We take a look at aid distribution in Haiti and the effect on Haitians fighting to survive in the aftermath of the earthquake. [includes rush transcript]