Regarding the raft with PLA: I've heard rumblings that it cannot be shut off, and it is built in to the software. Simultaneously I've also heard that the automatic bed leveling is not functioning yet. If that's the case, the two are probably coupled. If the tip of the extruder is not traveling parallel to the surface of the bed, a workaround solution could be to lay down a large, oversized raft - the bottom of the raft doesn't care so much if it gets bad adhesion in the areas where it's too high, because it's large enough that a good majority of it is sticking properly to the build platform. The top surface of the raft (which is what your model prints on) would then be starting out on a plane which is guaranteed to be parallel to the gantry - since it was built by it. I imagine this is the temporary solution until automatic bed leveling is integrated into the software.