Duplicate items
Enter a town and locate a training room.
Save the game.
Create a temporary character and remove (do not delete) one of the regular members of your party.
Add the temporary character to the party.
Place the item to be duplicated into the temporary character's inventory.
Remove the temporary character from the party and replace with the regular member.
Remove all characters from the game. Then reload the saved game. The item will be in both (temporary and regular member's) inventories.

Continue game with new characters
Create a party and complete the first three to five missions.
Enter a town and locate a training room.
Train characters, then remove (do not delete) all members of the party.
Quit game and restart program.
Add new characters. The new party will start where the older one left off.

Quick money
Create one permanent and six temporary characters.
Form a party with the six characters.
Funnel the party's gold into the permanent character's inventory and have that character purchase weaponry and other items.
Remove (do not delete) the permanent character from the party.
Create and add another permanent character to the party and repeat this process until all permanent characters possess the desired quantity of gold, items or weapons.