The $ sections relate to conditional compilation. They don't become part of the compiled source code. Only the branch that is true.
So in:
1436 $if $$no_op $then
1437 null;
1438 $else
1439 if ok_to_log(logger.g_debug) then
If $$no_op is true when you compile, then the final code is just "null;". Otherwise it includes "if ok_to_log(...".
These are part of the compile time settings. You can only change these by recompiling the package. For example:
alter package logger compile body PLSQL_CCFLAGS='NO_OP:TRUE';
or to make it false:
alter package logger compile body PLSQL_CCFLAGS='NO_OP:FALSE';
You can read more about it at
https://blogs.oracle.com/oraclemagazine/on-conditional-compilation 4. Not sure what you're asking here?