I do not understand your question. Are you asking whether bleeding the pressure to the wastegate actuator is a form of boost control? If so, the answer is no. It is a way to raise the boost pressure, but it is not done in a controlled way. An MBC would sit inline to the wastegate actuator and actually work to control the peak boost pressure in a precise way.
Get the ball and spring type. You can make your own with a minimum of tools and a few parts from the hardware store or you can buy one such as the hallman, the Joe P or any of the numerous others on the market.
And how the length of the hoses would affect overall performance. I know the shorter the lines from the controller to the turbo and actuator are best.... but would it be possible to run lines to the cockpit or would that just be a "major spike" waiting to happen?
TurboXS also makes a couple different MBCs. Check out http://www.turboxs.com/ . The dawes MBC looks like a good deal. I wouldn't run a line to the cockpit; it will affect how fast the MBC reacts. If what you're looking to do is be able to control the boost level from the cockpit, I'd consider the TurboXS version that allows you to electronically switch between 2 boost levels. It has 2 MBC's mated together.