I will try to answer some of your questions,
(1) What are the pros and cons of working with them for the eye area? -
Piggies are simply pigment, so you have the ability to blend them better, to build them easier and to mix different colors.
(2) Are glitter Pigment still not recommended for the eye area?
Yes - they are NOT recommended for the eye area or the lips because you don't want glitter in your eyes and I'd think you don't want to eat the stuff?
(3) What's the best brush for application when you really want to pack the color in?
I like to mix the piggies with the MAC Mixing Medium Gel - it's a gel type substance that will really give you the maximum pigment color and it will make the stuff stick - like glue. If I'm using the Mixing Medium Gel, I like to use a small liquid concealer type brush (much like a lip brush) - Chanel #4 is the one I use. If you're not using the Mixing Medium Gel, then use a creme type base and then I use a sponge tip applicator.
(4) Are there any differences between them and the pressed eyeshadow in terms of content, or if I were to grind the pressed eyeshadow would I get pigment?
This depends on the pressed eyeshadows you're comparing the piggies to. Most pressed eyeshadows have other chemicals in them, so - yes, you would get pigment, but you'd also get the other "stuff" that is in the eyeshadow.
(5) Is there anyway to turn the pigment into pressed eye shadow?
Yes, there are many instructional videos on youtube that will show and explain this process to you. (you can also find instructional videos on youtube about using the mixing medium gel with your piggies.
(6) Is there a top or something that you can get to control the mess?
I use the top to put a bit of the piggie on when not using a mixing medium, I use a MAC travel container for creme products (it's the small petrie looking dish container that MAC sells) for mixing the piggies with the mixing medium.
(7) What's the best way of putting them on without getting fallout?
See answer to question #3. Also, I wait to do my undereye so that I can swipe eye makeup remover if necessary after doing my eye lids.
What would you recommend for a newbie?
Sure! Why not? Just start out with a small amount of the piggie, practice on the back of your hand first, and then, practice when you're NOT going out. Then, you'll be ready for that time that you are going out
Please - everyone - correct anything that you feel I've said in error...
Hope this helps!