Fixes: 1) Correct default manager assignment in `Product` model; 2) Address potential division by zero in `AbsoluteFTPStorage`; 3) Ensure proper exception handling for missing `order` attributes in CRM gateway methods; 4) Rectify inaccurate string formatting for `Transaction` `__str__` method.
Extra: Refactor various minor code style issues, including formatting corrections in the README, alignment in the emailing utility, and suppressed pycharm-specific inspections; clean up unused imports across files; enhance error messaging consistency.