Have set (setq-default indent-tabs-mode nil). This works well when using the RETURN key. But I have also noticed that the TAB key stops inputting tabs.

Perhaps the TAB key is bound to some indentation command.

Could use of tabs and spaces be made simpler so that one can use both spaces and tabs.

Meaning that although indentation is done with spaces, pressing the TAB key still introduces a real tab?

Regards
Cholden