1. First of all, please define what you mean by "nothing". Second, what does this have to do with evolution?
2. A lot of science defies logic. Just because you can't conceive of something in your mind, doesn't mean it isn't there. Does the idea the electrons pop in and out of existence randomly make sense? Also again, what does this have to do with evolution? Abiogenesis is only one a quite a few hypothesis on how life on this planet began, and has nothing to do with evolution.
3. Have you never heard of RNA? Have you never heard of simple self replicating proteins? This is a classic argument from incredulity; "I can't figure out how it happened so it didn't happen." Or "We (humans) can't explain it, so it must be inexplicable." Sorry, that's not how science works. Biochemistry inevitably produces complex products. Amino acids and other complex molecules are even known to form in space.There are plenty of different ideas people have proposed on this problem and they are actively working on the issue. Again, this isn't evolution, this is in the realm of Abiogenesis.
4. When scientists use the word "explosion" they are using it differently from most others. The shortest estimated time span of the Cambrian explosion is 5 million years. Complex life had been discovered in early strata so the cambrian explosion was not the beginning of complex life. We see many transitional fossils within the Cambrian explosion. You are completely misrepresenting Professor Gould's hypothesis of punctuated equilibrium, and it's a hypothesis that most biologists reject.
5. Not every species went extinct when the dinosaurs did. We evolved from the species that survived.
I implore you to read a book about evolution by an actual evolutionary biologist. Even a high school biology text book could probably answer most of your questions.