How did he keep the wood from rotting before he had a chance to use it in building the ark?
I marvel at some of the specious arguments made against the historical record of the global Flood. Of what this huge ark was to be built was made plain by Jehovah: Make for yourself an ark out of wood of a resinous tree [literally, trees of gopher]. (Ge 6:14) This resinous wood here prescribed is thought by some to be cypress or a similar tree. In that part of the world what today is called cypress was in abundant supply; it was particularly favored for shipbuilding by the Phoenicians and by Alexander the Great, as it is even down to the present time; and it is especially resistant to water and decay. Doors and posts made of cypress are reported to have lasted 1,100 years. In addition, Noah was told not merely to caulk the seams but to cover [the ark] inside and outside with tar.
Over in England, still braving the notorious weather, is a wooden building near Ongar, Essex, constructed about 1013. A wooden temple in Japan, the Horyuji Temple, is centuries older.
How did he manage to cut and plain the wood for the ark? (That in of itself would have taken a very long time to do)
Uh, with tools such as axes, planes, etc.(Genesis 4:22) And hard work, of course.
How did he keep violent people from mobbing and stealing the wood (why cut your own when he has already done the job)?
The Bible does not say, but one possibility is he used the wood he prepared as he went. And of course, God protected Noah and his family, as he has protected his worshipers through all history.(Hebrews 11)
A boat catering to what would have been millions of species of animals with their specialized diets as well as their massive amounts of urine and dung would have been impossible for a small crew to handle.
There is nothing to indicate there were 'millions of species' on the ark. I'm pretty sure God thought about all this when he told Noah to build the Ark.
