Please read Darkstar's awesomely detailed description of the Structure of Forex Brokers:
http://www.forexfactory.com/showthread.php?t=7484
You will find many of the answers you are looking for, including the reasons behind spread widening.
http://www.forexfactory.com/showthread.php?t=7484
You will find many of the answers you are looking for, including the reasons behind spread widening.