The PT5071 is a rather nice piece of kit. It is an ISR (integrated switching regulator) than can produce 1.5A of clean 12v from a 7-16v input. It is made by Texas Instruments, the datasheet is on their website.
I'm planning on replacing my current L296 based power supply with a PT5071 and PT6625 based unit - pushes up the efficiency a lot and drops the heat produced.
I can't help on the diode thing - I'll only be using one of them in my design.