I can add on a bit to what Joseph and Konstantin have put in.
Regarding custom logos for your kingdoms, we currently don't have it planned, but I have asked our programming department about it, and it is possible. It is something a few of us think should be in the game, and we will probably put it in, but it all comes down to time constraints. We may not add a "use an image from your PC" style to it, because we know it would get abused, and it would also cost us to pay people to monitor those things (we'd like to use our budgets to pay more people to make DoF2 or DoF expansions). So more than likely if we do implement logos, it will be much like Guild Wars' cape design system, there will be numerous backgrounds/designs/colors you can use to create your own unique logo.
In game chat, there will be in game text chat, at this time we have no plans for in game voice chat. Not sure if any current RTS games use it, but if it becomes a necessity to you, you can always use third party programs like Team Speak or Ventrilio.