I agree with loosen one nut and then retorque it, before moving on to the next one. Torque readings should always be taken while the nut is still turning, as the friction goes up when it stops (sticktion).
However, the factory torque figures are given 'dry', so I don't add any oil.
For the ARP studs, I'd follow ARP's recommendation; which I believe is to use their special lube. If they give a torque value, I'd follow that; if not, use the factory spec. Adding the lube (and the 5 cycles of torque/release that they say to use) will increase the clamping force with the factory torque, and hopefully get the studs into the elastic range.