indent on tab

I’d like to be able (1) to tab to ident by some fixed amount, say two spaces, and (2) for RETURN to then preserve indentation – so if I am at two spaces of indentation, for example, and hit RETURN, I am still at two space of indentation.

Is there a way to do this?

For version 5: bind tab to "indentMore".

For version 6: See this for tab handling, and this command, which will do smart indentation when available, or preserve the indentation of the previous line otherwise.