2. Which color do you prefer? or Any other colors you think should be added?
Hard to choose since it's not completely clear which colors are (or will be) available. And anyway, resin is kind of random colored, so one particular color is only dominant, meaning it can be mixed with a completely different one, on the same panel.
On Heaven Gifts' site only a purple and a green version are listed. From those two, I would definitely prefer the green one. preferably mixed with some blue and white touches, like this: