a) yield - in this context means to produce or provide. "The field yielded a lot of grain" means the they were able to grow a lot of grain in that field. "the break LIFE yielded him" means that life itself has given this person good things, and other people envy him.
b) pattern makers - can be anyone who makes a pattern, like a weaver of Persian rugs for example. If you consider "civilization" as something that is woven, like a rug, then this person is saying that the "practical dreamers" are the ones who are choosing the pattern.
c) woolly - a sheep's wool is shaggy and unkempt. When people say "woolly west" they mean it is untamed and wild. "woolly thinking" is an expression which means unfocused and fuzzy thinking.
d) seedlings - are very young plants that sprout from seeds. The expression is saying that our reality was once a dream. For example, someone once dreamed of the internet, and that dream sprouted like a seedling, and now here we are corresponding over it.
e) humility - means to be modest and humble, and not to brag about things. For example, a person may think they are excellent at chess and they will brag and boast about this, but then they come across a much better player who destroys them in every game. Well this much better player will "teach you humility".