Answer 1

The output is undefined. It will give different results in different compilers.(8 8 6 8 in gcc, 5 6 6 8 in clang)
Don't do more than one prefix or postfix increment on a single line. It's bad thing to do. Avoid it.
https://stackoverflow.com/questions/4176328/undefined-behavior-and-sequence-points
https://blog.regehr.org/archives/213
https://en.wikipedia.org/wiki/Undefined_behavior