LNK306 based design generates humming sound

HI ,

We are using LNK 306 to get 12VDC  240mA from 230VAC INPUT.

This power supply is driving some relay (12 V),microcontroler and some leds(5v regulated from 12 V)

I need very small size power supply to fit in our product so I selected LNK306 NON ISOLOETD . With help of PI expert suit ,device datasheet ,application note I designed my ciruit.

Need some help for following points.

1.Is there any other IC  and topology from PI  available which will  better perform then my current design to get specified output.

2.Everything works fine but current design generates heat...is there any way i can decrease  temp by some 'c.I am using resistor for feedback.I have seen some transistor based feedback design in documents which claims to have little less heat dissipation then resistor feedback ,is that right?

3.It generates audible humming sound and as i turn on some relay, current drawing from power supply increases and hummning sound becomes more audible ...is this because something is not right in my design or its normal? any possible suggestion that solve this hummng sound issue.