Let's see if I can cover all the questions.
CU freebies are allowed as long as you follow the TOU. You should always have a copy of the TOU of any CU items you use available as a general rule. One time a designer here was accused by another designer of stealing her icicles. The accuser claimed she hand drew her icicles and that our designer's matched hers perfectly. She was right that they matched perfectly. But when asked where her icicles came from our designer was able to provide proof that hers were created from a commercial use brush. The accuser never did explain why her "hand drawn" icicles matched the commercial use brush, lol.
Your two previews can be whatever two previews you want them to be. Just be aware that only one preview will be in the newsletter. I'll be picking the one I consider to be the best of the two, so you'll want to make sure that one gives a good picture of what's in the kit, while the second one gives your preview a bit more depth and detail.
Brown is not part of the palette, so no. I'll check on metals, but usually if a metal is allowed it's included in the palette.
Use the eye dropper tool to get the colors. If you have any problems give us a yell, but this is how Julie gives the color palettes to the design team for the mega kits, so you should be able to extract the colors if you want to be a SAS-y Lady.
Yes, the two cluster elements count in the element total.
I'd say an alpha counts as 1 element. If it's upper and lower case, then it's 2.