Generally, you only have the white smoke at the initial ignition. Once the wood has started the white smoke will diminish.
It is a good idea to have the wood warmed up, putting it on the fire box for a few minutes will accomplish this, before adding to the fire box.
The size of the piece of wood depends on the size of your fire box. For your example, I would use a few pieces 2-3" in diameter.
This is what I would. Others may have a different opinion.
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