I liked the one before Tennant, too. Gotta love that sarcasm.
I love drinks like Smirnoff Ice and WKD. The latter just tastes like Powerade.
As for colors, that's something I'm super-opinionated about when it comes to OCs. You can only have so many colors that stick out; one or two's good, three's pushing it. Where those primary colors are on your OC should reflect their personality.
Dust/Medley (still deciding on names) - Primary color is vibrant and focused in her eyes; most of her major events are internal, and while she is capable of being cheery and, well, vibrant, she keeps that inside in favor of a more restrained approach to things.
Zephyr - Primary color is dull (the grey in her eyes) because she's emotionally dead inside, so apart from her purely mental struggles there's not a whole lot going on inside (for now). White in mane/tail reinforces sky theme (oo, sky-themed pegasus, how original) but also 'combines' with her eyes to create one of her thematic undertones; a storm. The grey eyes also double as a nod to her conflicted nature.
In addition, Rainbow Dash's rainbows could have easily been overdone, but if you look at her mane in proportion to her size, it's a much smaller proportion than those of the other five. Keeping colors on a leash, see.
Whereas someone like, say, Pinkie, is all vibrant colors (pink) and has baby-blue eyes because she's very outgoing. Or take Rarity, whose colors are more refined, balanced, like her royal blues eyes. Colors are extremely important and unfortunately, often overlooked when it comes to OCs.