Yes they do (been discussed here before), and yes. I think it is only human.
I'm sure it's the same as men checking out woman's breasts so yes, I have been known to check out a man's 'package' although it is definitely not the first thing I zone in on.
Yes I have noticed women looking at both the ass and the bulge on guys.
Oh yes, we belong to several clubs, the girls including my wife love to check out the guys bulges.
My wife just walked past me and noticed I had a bulge going on, stroked my cock through my shorts and left me needing relief.