Amen. As you can see from the rebinding screen, there are precious few hotkeys. Why can't it be more like GalCiv 3, where you can tab through pretty much everything?
What do you mean "characteristics"? Each bar for a resource represents 1 to 3 points of base production (you won't know the actual base production of a planet until you colonize it). Generally hot planets are good for industry, cold planets are good for science, fertile planets (fish icon) are good for food, sterile planets (fishbones icon) are good for dust. Size determines maximum population, which can be raised by leveling up the planet with the options that unlock at rings 3, 4, and 5 of the economy and trade tech. Any anomalies, strategic resources, or luxury resources are tooltipped.
Everything is tooltipped. Different types of populations are affected with different strengths by different actions. It's mostly intuitive, but the tooltips on the population details, for instance, explain exactly what actions boost which faction's standing. Which is indicated on the system screen under "system representation". Furthermore, lots of actions tell you what faction they'll boost. For instance, every tech indicates which faction it boosts.