phono stage placement

Correct, shorter is better, especially on the phono. On MC it is even more important. I have tried short and long with a ARC PH3SE and can always tell the difference.

How long is "long"? Is 1 meter generally acceptable for MC?

1m or 0,6m are the usual standards between table & phono. Use a low capacitance cable if you can (low inductance of course).

You don't need that long a cable anyway. Just place the phono next to the TT.

I used to try and keep phono cable as short as possible (0,5m being sufficient in my system), I was surprised though to find a number of reputable manufacturers offer 1,25m as standard length. At the moment, I am awaiting delivery of a Synergistic Research Tricon for auditioning, Ted Denney actually advised me not to go shorter than 1m with this cable.