In a non-word processing context, is it okay to have key presses do actions without having the user preface them with ctrl, alt, shift or command? If I do have them just be single key presses, do they have to follow the normal shortcut key layout?
Also, what's the best practice for teaching people what keys do what?
In a non-word processing context, is it okay to have key presses do actions without having the user preface them with ctrl, alt, shift or command?
On a full keyboard that's what the Function Keys do. You could argue that function keys tend to be underutilised nowadays. Without the use of the preface key you can't use the other keys on the keyboard unless you're really sure that you are never going to want users to input their primary character.
"Also, what's the best practice for teaching people what keys do what?"
You put 'clues' on the menus next to the text commands: eg "Paste - Ctrl+V"
This is an existing interface standard.
Regarding teaching people, one approach is to have a tool tip that appears about 3 seconds after hovering over a control. The tooltip text includes the hot key, say at the end in brackets.
This way, beginners can learn the hot keys but intermediates / experts aren't bothered by the tool tips once they have learned the hot keys.
Also, tooltips are contextual, which helps to associate the action to the hot key.
Short answer: no, it's not always necessary.
Slightly longer answer: it's probably necessary for most scenarios.
Pro software like Adobe's Creative Suite and Apple's Final Cut Pro use lots of shortcuts which don't depend on modifier keys.
In general in these applications, modifier keys are still used for shortcuts to menu items (generally actions), but not for actions exposed as tools in the interface (which normally simply change the application's mode).
For example, switching to the marquee selection tool in Photoshop is done by pressing m, but actions like 'Select All' are Cmd-a.
They do use modifier keys for actions that are not the defaults for the function (using Option/Alt with the shortcut will do the next option in that tool's set, e.g. ellipse select tool).
The benefits of eliminating the need for modifier keys include being able to use the keyboard with one hand while using the other to control the mouse or graphics tablet. That's made especially easy because you tend to use the same keys a lot in those applications (e.g. pressing m in Final Cut Pro places a marker in the timeline, something you may do many times in a row, and which you need to be able to do without taking your eyes off the screen).
These apps, by virtue of their complexity, sometimes invent their own paradigms for many things, ignoring platform conventions. Even in these apps, however, it's important that no single key, when pressed, has a destructive impact on the document.
All that doesn't make it a reasonable choice for consumer apps, though. For most apps, it's going to be much more work to train users not to use a modifier key than to just add them to the shortcuts in the first place.
In a similar vein: don't expect Mac users to use Ctrl shortcuts!
