As far as 3d programs go everyone has their favs and some are better for certain tasks. I tried Maya for a bit and although I got some terrific results I just didn’t have the time to really dive into it. Cinema 4d is very intuitive and you can get great results without spending a year locked in your room. I also hear great things about Blender, it’s a free/ open source 3d App that a lot of people swear by. There is also RealFLow which specializes in fluid simulations ( as well as particles and dynamics).
Back to Ae…:) for the highlights, I would use a white or light colored solid, mask out the shape you want, feather it then switch the transfer mode to Add or Screen or the like, then parent it to your “color” layer and animate it. Same sort of idea for the Shadows. There is a great tutorial on Video Copilot called “The Ring” or something like that. Andrew Kramer has got some great tips and tricks in there for making a 2d object look 3d using masks to make highlights and shadows.
For the drips you could try a particle generator. CC particle world might do the trick depending on the level of realism you want. Or you could look into Trapcode Particular which lets you use custom layers as particles that you can make into anything you want ( even animate them ) This might be the way to go for a lot of what you’re trying to achieve.
For the Mr Mercury idea I would again apply a mask to the layer in the shape you want the paint to eventually create then play around with the effect settings. Birth and Death sizes should give the effect of smaller blobs coming together and filling in to make a solid shape.
I’ve emptied my head of any ideas I have. I’m sure there are a lot more!
Best of luck!
Trev