Re: transfercase and pinion angles
Yeah the transfercase angle does point down twards the rear in a stock configuration, so your arm is not bent. I noticed this also when I did my spoa pads.
Most people wont get bad driveline vibes from the front, unless they are baja-style speeding in 4wd on a very smooth surface.
I would try a single cv shaft in the front if you are getting bad front d/l vibes.
And your also right on the 'matching angles'...I think the rear is far more important to align.