[Amps] HV step start

[Steve Flood]

Been gathering some parts to get my amp power supply together.
Mine is basically an SB-220 transformer set up for 230v and the secondary will run about 2700v at 500-600 mA.
I have a few questions regarding a step-start (soft-start?) in the primary leads.

1.  Should there be a step-start resistor in both primary legs or is just one leg adequate?
2.  Some sample circuits show the step-start relay across one side of the mains supply (120vac) with an electrolytic across the coil, a series pot for adjusting time delay, and a series diode.  Now some samples indicate a 120vac coil and others a 120vdc coil.  It seems to me the diode and pot provide enough rectification and smoothing to go with a dc coil here.
3.  Am I assuming correctly that only a couple seconds of delay are needed and that the typical 25 or 50 watt resistors are an adequate rating for this short delay?

Steve KK7UV