R3, R6 1M resistor:
Most small resistors will not survive 600 volts. You need to find a high voltage resistor. (or use resistors in series)
Next find the average voltage and current. watts. Choose a resistor that can withstand that power.
A 1W resistor with 1W of power will almost melt the solder.
I usually run resistors at 1/2 power to keep the temperature down.
(you must choose a real part before you can get the temperature)
D1,3,4,5:
Spend some time with the data sheet. It looks like the maximum temperature is hit at 1.1V @ 1A. So it is a 1.1 watt diode. Max temp 150C junction temperature.
Question to you; Is this the right part? Is your average current above 1A or below 1A?