Building a Switched Mode Power Supply

I am planning on building a switched mode power supply or SMPS. The circuit will have one +12V,0V supply, and two +12V,0V,-5V supplies. I have been looking at transformerless power supplies to power my driver circuitry (Fig1). I chose this power supply because it has no transformer and I can save space on the PCB. How could I get this circuit to supply more current? Would the zener diode get hot? To drive a pair of FQP9N50C MOSFETs I am using an IR2110 FET driver IC (Fig2). Would I need any modifications to this circuit? What would be the best arrangment of the MOSFETs? A half bridge converter or a full bridge?