KAK, I still think you should get a white cat too, then it would be easy to give it a name like Snowy!
More name ideas, I know some have been mentioned already,
Sleet(I like it too WolfQ), Slushy, Smoggy, Hazy, Smokey, Steely(that fits with the name Flint and steel gray skies),
Sky can also be short for Skylar, Windy(but that seems to be a girl name),how about Gusty or Gus for short?
Good luck with picking a name!I hope you will post some new photos soon!

About your meowing question, when my neighbors got a kitten and it kept coming into our yard, Samantha would hiss at her to scare her away and she would answer with this pitiful meow as if pleading don't hurt me! Now that they have had the cat for a few years she still comes in the yard but usually leaves when she sees Samantha. I think it may mean that the new cat is saying "Please like me" but it doesn't sound like Flint will be the alpha cat. Which one of your cats seems to be the boss one?