How to get Chess Software to play itself? and a few other questions.

Hello all, I hope this is the correct forum for this, but if not, Mods, feel free to move.

I have a Mac and have Deep Shredder 13, HiArcs Chess Explorer, and ChessKing.  I know when I used to use a PC, some of the Chess Software would allow you to play itself, but on these three programs, I do not see that option.  Do any of you know if it is possible?  So far, Deep Shredder 13 is my favorite.

Also I have had all 3 analyze games I have played here, at their deepest analyzation settings.  All three seem to be pretty close at how they access the games.  I know they all have different engines.  Is there an engine that seems to be the accepted BEST engine?  

I think the newest version of the Hiarcs Mac Chess Explorer advertises engine matches as an option. I'm not sure about older versions.

Mine is only 2 months old so I think I have the latest, so I might need to poke around a bit.