From my experince, best is to shoot in spiral, start from subject face and snap picture move in spiral outward. Its easier to trace your step too. start wih subject face because they might move during the brenizer attempt. Shoot quickly to avoid subject movement.

Crank up ISO to get enuf shutter speed.
Higher iso may induce noise, but when u compile many2 pics it is unnoticable

Shoot at low resolution MP is enough.
Compiling 40> images will get you very huge file in the end

I'd usually just shoot in JPG , so i will get the settings to be most correct. Post process only after stitching

Shoot in Manual mode
expose to subject face and AEL the rest. iso , WB, shutter, aperture should be fix so there be no inconsistency on stitch image.

ive did them handheld, without even modopod and most of the time it works.
Best if you overshoot so you would get extra space to crop later.

Software wise, i tried compiling panorama in PS, out of 5 brenizer attempt, PS cs5 unable to stitch 3.
So i opt out for Microsoft ICE (image composite editor), works very well everytime.
Also Microsoft ICE is really fast and RAM utilization is good.
Unlike on PS, stitching like 40images would eat all your RAM & may end with crashing the PS haha

Best if shoot with lens with very minimal distortion to no distortion.
I'd suggest 85mm and longer. With 50mm you'll get a unique like image but very distorted in the end.

How many image should take?
Depends on your composition/final image, whether full body/half body/etc. also depend on your distance with subject, nearer u may need to shoot more. Always remember more is better.