For an ECN account and MT4 platform - FxView and Alpari. I found them much transparent and there aren't any hidden costs.
ECN brokers do not trade against their clients. They provide direct connection between buyers and sellers. Mainly dealing desk brokers are criticised for taking counter position to their clients.
It's always in your hands to place a stop loss order. I don't think that this is something you should try to find in a broker. There are lots of other important things to be looking for while choosing a broker. Right placement of a stop loss is something you need to determine by yourself .
There are plenty of brokers who offer ECN accounts. If you can't find one in USA, you should consider offshore brokers. They are generally more flexible and provide additional features.