1. The turtle implies that the computer of the person associated with it is running slowly, thus slowing down the game. Ie, their computer is trying to do to much at once.
The yellow dot means that the ping between your computer and theirs is between .5 and 1.0 seconds. Ping is the amount of time between when your computer says hi and his computer responds back. The lower the ping, the smoother the game runs. Yellow is generaly ok.
A red dot means that the ping is over 1 second, and this is generaly bad, no dot at all means its less then .5 seconds, and this is great.
2. Resources change as you gather them, odviously, and as you repair buildings/ships. They also change when you build units, and when you upgrade technologies. They change when you tribute resources, or when resources are tributred, about the only other time they change is when you delete the foundation to a building, you regain some resources back the amount depending upon how complete the building was.
3. For non shang civ's, in general you want your first 5 villagers on food, thus I would explore with my first 5 untell I found food, at which point the nearest 5 would converage on it, the remaining would goto wood, this also assumes a default resource start