Wet wood burns cooler than dry wood, but burns relatively longer. Heart wood burns hotter than sapwood in general. Rotten wood is good for producing smoke, but not heat or light. Charcoal burns hotter than the wood it was made from as the volatile gases which produce flames burn at a relatively low temperature. So your coals are the hottest part of the fire, not the flames.
Light comes from the burning gases.
The firewood you can actually get always burns better than the firewood you wish you had, but you'll need more of the poor stuff. Think of wood as calories. Better wood has more calories per piece, so can do more work. The easiest, but slowest way to get a bed of coals is to build a huge log fire and wait a few hours. This takes the least effort and the most wood.