looking fo documentation for module files

[Gribouillis]

this is unclear. at first it says it is automatic. then it says what to call. is coding such a call going to suppress the automatic import?

I think it is very clear:

• If the python executable is invoked without the -S command line switch, the site module is automatically imported and site-specific paths are appended to the module search path.
  
• If python -S is invoked, this doesn't happen, but your code can use import site, and the site-specific paths are appended only if you code calls site.main().
  

Changed in version 3.5: Support for the “site-python” directory has been removed.

In the past, there was a directory lib/site-python on Unix and Mac. This directory no longer exists.

is there an explanation of how things get run when doing a command with the -m option? are arguments in sys.argv as is done for normal commands? is there an advantage to making a command/script be run this way?

The advantage is that a python library can be used as a python program. You don't need to write a module plus an executable script. For the effect of the -m switch on sys.argv, here is the doc.

i just want to have a place to put modules in that may be for user coded scripts run from their home directories

I suggest $HOME/.local/bin