Group Items and showing the customer credit in the invoice

First of all, I am lucky to know about that program, I am using it from almost two years and i recommended it to many friends,
Secondly, I hope you can add feature to group many items under groups in inventory especially if i have almost more than five hundred items and sometimes i forget the description and the code of the item,
Plus, I hope i can see customer credit when i create new invoice for the same customer, i think that will be very special feature for users,
Your quick response will be highly appreciated,

Use hierarchical names then the alphanumeric sort order will group items for you.