earth lift resistors

I have previously been advised to use 100R as earth lift resistors, and have been using wirewound cerramic cased ones rates at 3W with success.

Now an engineer proposes to install a l meg (one meg) 'earth leak' resistor in my valve amp. He says he will bypass this with a 0.1mf capacitor.

Can anyone advise:

i) whether the l meg is as safe as the 100R?
ii) what the purpose of the 0.1uF bypass is and whether it increases safety?
iii) what wattage rating and type of resistor should be used in a valve amp, assuming that 1 meg IS appropriate?