For 3, the answer is my handling via $SIG{'CHLD'} is sufficient, if done properly. I wanted the parent process to check the return value of each child process, and wanted the child processes of the parent to just reap their child processes, so the function called when receiving the child signal had to handle the reaping differently for the parent than the children.

For 4, yes, you have to reset the STDERR and STDOUT if you want them redirected in the child processes.