I've only just seen this thread, but the photos of the quilt in progress look LUVERLY.
I agree with Low about not needing to make bias binding unless you are binding curves, but if it's done now then it's done and don't beat yourself up over it.
Putting a thick layer of fabric and wadding through the machine would, I think, mean lowering the pressure on the foot. Only alter the top tension if it's gone out of kilter with the bobbin thread - and don't mess with the bobbin thread.