No, I'm not Dominican, but have lived off an on in the country for about 5 years. I wont comment on the rest, because each person is entitled to their opinion. I'm from Detroit by the way, and have seen far worse corruption and much more murder than I have seen here. More people are murdered in Detroit in a year than in the entire Dominican Republic, but that's neither here nor there. Again, not everyone is corrupt. I have had the PN help me on occasion, and on one occasion when my home in Santiago was broken into, they retrieved most of my property without me having to grease their palms.
A lot of it is perceived attitude and people can smell one a mile away. If you approach them with the attitude that because you're a foreigner, you're superior to them, you will be treated with disdain and possibly worse. Again, the average PN foot soldier earn about 3,000 pesos a month, what many of earn in half a day or an hours work.
As far as the average PN enjoying killing, that remains to be seen, I think there's a lot of conjecture here.
You know why they retrieved your things so fast? They were the ones that STOLE YOUR STUFF!!! Don't even TRY IT you paid them something. HOW MUCH did it cost you?