Can't open your project here at work, 'cos I'm stuck with CS4, but here are my thoughts:
isn't there some way to mirror the first wing with an effect?
Sure. Effects --> Distort --> Mirror
but the wing was mirrored *inside* the mask,
Rule No. 1: In case of doubt, pre-compose. AE's rendering order is quite specific. There's some part on that in the online help with some external linkage e.g. to the relevant article from the Chris & Trish Meyer books. That should help to clarify matters.
2) I did the snake reveal using the old "soda straw wrapper" mask technique (watch the mask layer animate by itself - it looks like a crinkled soda straw wrapper unfurling in reverse back over a straw). Is there a more elegant way to do this? It seems this should be automatable. The mask for the other snake is the exact same layer, duped and flipped. Is there a way to handle this with some sort of mirroring, as well?
Again ther answer is probably in pre-composing and using stuff as a matte rather than masking directly. For reveals, learn to work with the transitions and the laready mentioned Mirror effect as well as additional multiplication effects like Motion tile, CC Kaleida along with distortion effects leik Transform, Bezier Warp, Corner pin. You can create tons of looks just with that by keyframing a few parameters and adjusting values...
3) I'd like to have the orb reveal using a circular wipe that starts really small and wipes outward from the center as an ever-expanding circle. All the effects seem to want to wipe around the circle like a clock hand. It seems like this should be simple to do... but how? (I realize I could use an animated matte layer, but figured there was a simple effect that would accomplish this)
Effects --> Generate --> Circle, Mode: Stencil Alpha, enable the Invert option - magic!
Hmmm. Pre-composing makes perfect sense. I still have to get comfortable with the various ways of approaching things.
Pre-composing/matting would definitely help on the snake reveal, as well... that would let me create one mask and use it twice. The only way a canned transition would work is if there is one that will reveal along a path, like you might use for any kind of organic, non-straight shape that needs to wipe along its axis. Maybe matting the woven helix of the snake with a thick;y stroked path? Isn't there some sort of parameter that lets you animate the drawing of a line?
On the circle thing, I just created a new solid above my orb, applied the gen circle effect, aniamted radius and linked it as a matte. I'm not following what you are getting at with the stencil alpha and the inverted circle.
Out of curiosity, what sort of AE work do you normally do?