Being a trap shooter myself I would ask why would you choose a trap gun for hunting? Generally regardless of manufacture they will have extremely straight stock dimensions designed to make the gun shoot a high point of impact above the bead. Getting one's head down in the correct place on a trap stock is easily done on the trap field as you pre mount the gun and call for the bird, in field shooting with quick mounts and shots taken as the gun hit's the should it can be very difficult to get one's head in the correct position with such a gun.
That said the gun likes nice and you don't see the trap models very often, I can't remember the last time I have seen one.
As far as loads. You don't need to shoot heavy loads (but you can), trap loads are sufficient. If you reload you have choices. There are two schools of thought, I prefer #6, others prefer #7.5 or #8. If you don't reload economics forces the choice of smaller shot.
Thanks for the reply as it is the only "shotgun" I have so it will have to fill a dual-purpose role-CROWS AND CLAY BIRDS!! POP-A-CROW TODAY, TOMORROW, AND EVERY DAY!! A CROW A DAY MAKE THEM STAY AWAY!!!!!!!!!!!
If I were you I would consider buying an extra "field" stock with better dimensions for using the gun for hunting. An extra stock for a Ithaca 51 is available via gunbroker and ebay. They are a pretty simple job to change out. Good luck.