You can quote anything, literally anything. Why wouldn't you be able to? The only caveat, if you can call it that, is that you can't necessarily 'write out the resulting code sexpr readably (for example, functions are not, as a rule, writable).
The only reason why you need to quote certain things at all is because the arc compiler is very picky about its input -- it cases on the type of the sexpr it's compiling, and if it doesn't recognize the type it throws an error -- but things inside a quotation escape this examination. If this weren't the case, and it instead just passed them through, then functions could be embedded directly instead of quoted; and everything (I think) other than symbols and lists evaluate to themselves in mzscheme.
